*-.
           VIEW OF THE


    METAPHYSICAL AND PHYSIOLOGICAL


          ARGUMENTS


              IN FAVOUR OX


MATERIALISM.
BY A PHYSICIAN.
noMffov cf'*<8g»vj tat J' oq&x\(Aoia-iv iffo-Qcti

Er it <?>*&> Kctt ohto-o-or

 Grant us day light and fair play.
                         Homer.
PHILADELPHIA.

     1824. 
^ -A
V 
     THESE PAGES






 ARE RESPECTFULLY SUBMITTED






          TO THE














          OF THE







   UNITED STATES,







E MOST COMPETENT JUDGES OF THE ARGU-




   MENTS CONTAINED IN THEM. 
 
ON THE  SOUL.
    Man consists of a body, which, when living,
exhibits a peculiar organization, and certain phe-
nomena connected  with  it,  termed intellectual;
such as perception, memory, thinking or reason-
ing, and willing or determining.   When the body
ceases to live, it becomes decomposed into car-
bon, azote, hydrogen, oxygen,  phosphorus, and
lime ; and perhaps another  substance or two: all
of them, similar to what  we find in the inanimate
material bodies around us.  We differ from them
so far as we can judge by our senses, in no way,
but in possessing a peculiar organization  which
those bodies have not.   But as  no configuration
or disposition  of the particles of which our bo-
dies are composed, can amount to any thing more
than varieties of position—varieties  of  matter
and motion, we have no reason to ascribe percep-
tion,  memory,  thought,  or will, to any form of
matter and motion, however varied.  From mat-
ter and motion, nothing  but matter and  motion
can result.   The phenomena of intellect are too
dissimilar to allow  us to consider them  as the
result  of, or  as varieties of matter and motion.
We must therefore  recur to some other principle
as the source of intellect: and that cannot be the
body.  It must be something different from mere
matter and motion, something immaterial,  some-
thing that has no relation to matter: that  some
                    A  2 
6
thing, be it a separate being, or a  separate prin-
ciple, is the Soul.  Will any arrangement of car-
bon, azote, hydrogen and oxygen,  produce a syl-
logism ?   Having no relation to matter, being es-
sentially immaterial, this source  of intellect is
not, like matter, liable to decomposition and de-
cay : it is therefore immortal: it  dies not when
the body dies.  It puts  a future state, therefore,
out of doubt, for it lives  when  the body is no
more.
  Such are the views  generally  taken  of this
question by  those who believe  in the separate
existence of an immaterial Soul&s the  cause and
origin of all the phenomena termed mental or in-
tellectual.   With them, it is  absurd to ascribe
the sublime fictions  of poetry, or the sublimer
disquisitions of Newton and La Place, to a mere
arrangement of assimilated particles of the gross-
est kind ; possessing, before their entrance  into
the body, and when thrown  by the exhalant ves-
sels out of it, nothing approaching the nature of
intellect under any of its denominations.
  In the present view of the  subject,  all argu-
ments  of a  theological nature  are  excluded.
They can be considered apart: and  they are  to
the full as difficult of solution, as  the arguments
deduced  from natural phenomena  ; and ate pro-
ductive of as much practical discrepancy.
  The lmmaterialists of modern days are led on
Still further.   They say that the tendency to or-
ganization itself,  and all the results  of that ten-
dency, must  have  been originally imparted and
communicated  to inert matter, which could not
have assumed this tendency by any  effort of its
own.   That organization, life, and the properties
connected with life, as  feeding,  digestion, assi-
milation, excretion, &c. as well as the phenome-
na termed intellectual, cannot  arise  from any
known property of matter as such ; and therefore
must have been originally impressed by that Be- 
7
ing to whom all creation is to be ascribed.  That
the phenomena  termed intellectual  are clearly
distinguishable from the other phenomena of liv-
ing organized matter,—they are peculiar to the
human species—not to be accounted  for from the
common properties of organization  or  life, and
are therefore owing to a separate and  distinct
communication  from  the author of  our common
existence.   That  not being  ascribable to any
form of organization,  or to be regarded as the re-
sult of it, they must of necessity  be ascribed to
some separate being  of a different and superior
nature from matter; destined during the present
life to act by means of the bodily organs.   This
separate being  is  the Soul.  It  is  granted that
we are not to argue from  the possibility of any
thing, to its actual existence, (a posse ad esse
non valet consequential but when  the phenomena
cannot be explained by any known properties of
organized or unorganized matter,  we are of ne-
cessity driven to something else than—something
beside matter—something which is not matter, to
explain appearances that are not material.
   1 do not know how to state better, more fairly,
or  more forcibly,  the views taken of this ques-
tion by  the writers who contend for  thp separate
existence of the Soul, as a being perfectly imma-
terial, and  by consequeuce incorruptible and im-
mortal.
   On the other  hand, the Materialists,  who as-
cribe all the phenomena termed  intellectual, to
the body ; and consider them as the properties of
organized matter, the result of that organization,
—reason as follows:
   Their arguments may be considered, as 1. Me-
taphysical, and  2. Physiological.
   To begin with the first class.
   1.  The  only reason we have for asserting in
any case that one  thing is  the property of  ano-
ther, is the certainty or universality with which 
8
we always find  them accompanying each other.
Thus, we say gold is ductile, because we have
always found gold, when pure, to be so.  We as-
sert that manure will nourish a plant, that mus-
cular fibres are irritable, that the nerves are the
instruments of  sensation, &c. for the same rea-
son.   Let the reader sit  down, and describe a
mineral  by its  characters; and he  will have no
doubt of the truth of this assertion.
  ^Moreover,  finding  by experience that  every
thing we see has some cause of its existence, we
are induced to ascribe the constant concomitance
of a substance, and any  of its properties to some
necessary connexion between them.    Hence
therefore, certainty  and universality of concomi-
tance is the sole ground for asserting or supposing
a necessary  connexion between two phenomena.
And we  cannot  help believing that like conse-
quences will invariably  follow like  antecedents
under like circumstances.
  There is a  necessary connexion between such
a structure as the nervous system in animals,
and the  property of sensation, or as it is often
called, perception—the  property of feeling, of
being  conscious of  impressions  made upon our
senses.   For  there is precisely the  same reason
for making this assertion, as there can be for any
other  the most incontestable; namely, the  cer-
tainty and universality wherewith (in a healthy
state of the system)  we  observe  perception  and
the nervous system accompany each other.   The
seat of perception,  so far  as  we  know from the
facts of anatomy and physiology, is situated at
the internal sentient extremity of the nerve im-
pressed.  But be it  there or elsewhere, as it ma-
nifestly belongs to  the  nervous system, that is
sufficient fpr the purpose.  It must be somewhere.
Let the  reader, according to his best judgment
from known  facts,  place it where he thinks  fit,
and it will equally serve the  purposes of my ar- 
9
gument.    Perception,  sensation, feeling, con-
sciousness  of impressions  (for all  these terms
have been used synonymously ; I  prefer the first)
is a property of the nervous apparatus belonging
to animal  bodies in health and life.  When the
sentient extremities of a nerve,are excited or im-
pressed, perception is the  certain instantaneous
result, as surely as  the peculiar  weight, colour,
ductility, and affinities  of  gold are the result of
gold,  when obtained pure.  These properties are
inseparable.  You must define gold by them : in
like manner, you must define  the  properties of
the nervous system by perception—sensation.
  I consider this argument as conclusive; unless
it can be shewn how perception results necessa-
rily from  something distinct from, and indepen-
dent  of the nervous system, or that, whether this
can be shewn or not, the assertion that percep-
tion does so result, implies a contradiction, and
therefore is at  all events inadmissible.
  That certainty and  universality of concomi-
tance is the sole ground for asserting a necessary
connexion between  two phenomena, or that the
one  is the result  of  the other, is so true that if
this be false, no argument from induction  can
possibly be true: for all proofs  from induction
imply the  truth of  this.  And as no  direct con-
tradiction has ever been attempted to be shewn
in the assertion that perception is  the  result of
organization—as the matter of fact, so far as our
senses can judge, is  plainly so,—and as no Im-
materialist  has ever  yet pretended  to accouut
how perception results  from an immaterial rather
than a material substance, there  is nothing more
requisite to prove that perception  is really and
truly the result of our organization.  The  argu-
ment then stands thus: Certainty and universa-
lity of concomitance between two or  more phe-
nomena, are the only direct reasons-we have, for
asserting or supposing a necessary connexion be 
10
 tween them.  The property of perception and a
 sound state of the nervous system under excita-
 tion, are certainly and universally  concomitant.
 Therefore this concomitance  furnishes the only
 direct reason  we have for asserting a necessary
 connexion between perception and the nervous
 system.   But  this reason is  the  same that  we
 have for  asserting a necessary  connexion be-
 tween  any other phenomena  whatever.  There-
 fore we  have the same reason for asserting a
 necessary  connexion between the property of
 perception and  a sound  state of  the  nervous
 system, as for asserting  the same thing of any
 other phenomena  whatever.   It will  be under-
 stood of course,  that the nervous system  must
 be  excited,  before the excitement can be per-
 ceived; and  whether we adopt  Hume's  phra-
 seology, or that of Dr. T. Brown in his Treatise
on Cause and Effect, the argument will be exact-
ly the same.   In all  cases, where the necessary
 connexion between two  phenomena is such that
the one is denominated a. properly, and the other
 the subject of which  the  first is a property, the
 property is universally deemed to  result neces-
 sarily from the nature or  essence of the subject
 to which it belongs.  But  as perception must be
 a property of  something;  and as it is uniformly
 connected with a sound  state of the nervous sys-
 tem, perception is a property of that system, and
 results necessarily from  the  nature or essence
 thereof.
   Such is the  proper and direct proof of the doc-
 trine of Materialism; which,  so far as I am ac-
 quainted  with the controversy, remains  unan-
 swered.   But this doctrine  will receive  addi-
 tional support, if the opposite doctrine of Jmma-
 terialism can be shewn impossible or improbable,
 I shall endeavour to do  both. 
11
Of the Impossibility  of the Existence of an  Im-
    material, Indiscerptible., Immortal Soul.

  2.—(a)  The  Soul hath  all the properties of
matter and no other: or it hath some properties
in common with matter, and  some that matter
hath  not:  or it hath  no property in common with
matter.
  In the first case, it is matter, and nothing else.
  In the second case, it is  partially material.
  In the third case,  it  is in no respect or degree
material.  This last case is the  only one  of the
alternatives that the hypothesis of Immaterialism
can consistently maintain:  for in so far  as  the
Soul is material, it  will  be discerptible, mortal,
and corruptible.
  (6) But let the Soul have no property in com-
mon with  matter.  Then I  say:  Nothing can act
upon another but by means of some common pro-
perty.   Of this we have not  only all the  proof
that induction of known and acknowledged cases
can furnish, but that additional proof also which
arises from the  impossibility  of conceiving how
the opposite proposition can be true.  You can-
not  erect the  Colisceum  at  Rome by  playing
Haydn's  Rondeau.  You cannot  impel a ray of
light by the mace  of a billiard table, and so on.
This proposition is every where admitted, or as-
sumed, in treatises on  natural philosophy.
  But by  the  proposition,  the Soul hath no pro-
perty in common with  matter,  and therefore it
cannot act upon matter.  Whereas by the uni-
versal  acknowledgment of Immaterialists,  the
Soul acts  upon and by means  of the material bo-
dy :  but it is a contradiction to  suppose that the
Soul can and cannot, does and does not, act upon
the material body: and  therefore the hypothesis
involving  this contradiction  must fall to  the
ground. 
12
  3.—(a) Whatever we know, we know by means
of its properties, nor do we, in any case, know cer-
tainly any thing but these.   Gold is heavy, yel-
low, ductile, soluble in aqua regia, &c.  Suppose
gold deprived  for an instant  of all these proper-
ties,—what  remains,  would  it  be gold ?   If it
have other properties, it is  another substance:
if it have no properties remaining, it is  nothing;
for  nothing is  that  which hath no properties.
Hence, if any  thing lose  all its properties,  it be-
comes nothing; it loses its existence.
  (6) Now the existence of  the  soul is inferred
like the existence of  every thing else,  from its
supposed properties,  which are the  intellectual
phenomena of the human being, perception, me-
mory, judgment, volition.  But  in  all  cases  of
perfect sleep—of the operation of a strong narco-
tic—of  apoplexy—of swooning—of  drowning
where the vital powers are not extinguished—of
the effects of  a  violent blow on  the back  of the
head—and  all  other leipothymic   affections,—
there is  neither perception,  memory, judgment,
or volition ; that is, all the properties of the soul
are gone, are extinguished ; therefore the soul it-
self loses its existence for the time ; all evidences
and traces of its existence are lost;  pro hac vice,
therefore, and during the continuance of these
derangements of the  nervous system, the soul is
dead, for all  its properties  are actually  extin-
guished*  The Soul  therefore  is not immortal,
and of consequence it is not immaterial.
  (c) This disappearance of all intellectual phe-
nomena in consequence  of the derangement of
the nervous  apparatus of the human system, is
easily accounted for,  if they be considered (as the
Materialists  consider them) no  other than phe-
nomena  dependant upon  the nervous system in
its usual  state  of  excitement by impressions  ab
 extra, or motions dependant on association origi-
 nating ab intra.  On this view of the subject, all 
13
is natural and explicable.  But if these intellec-
tual phenomena are the evidences and properties
of a separate immaterial being (the Soul) then
comes the insuperable  difficulty—where i= the
subject itself when all its properties, all evidences
of its existence are annihilated; though but for a
day or an hour   A materialist can easily account
for returning animation  by renewed excitement
from the unsuspended action of the functions of
organic life.
  4.  No laws  of reasoning  will free us  from the
bondage imposed  by matters of fact.   It  is im-
possibly to deny that all these intellectual phe-
nomena/these peculiar properties of an immate-
rial soul,  these only evidences of its existence,
are also properties of the body:  for where there
is no  nervous apparatus, as in  vegetables, they
never  appear; where the nervous system i -. de-
ranged by violence, or by disease, or by medicine,
these  phenomena are also deranged, and even dis-
appear ; whe*n the body dies and the nervous sys-
tem with it, all these phenomena cease, and are
irrevocably gone ;  we never possess after death,
so far as our senses can inform us, the  slightest
evidence of the existence of any remaining being
which, connected with the body during life, is se-
parated from it at  death.  This may be asserted,
but there  is not one solitary fact to prove  it:
when  the  body  dies, no more perception, no more
memory, no more   judgment, no more  volition.
So far as we can see, these die with the body,
and exhibit  no proof of their subsequent exis-
tence.   These phenomena, are phenomena then
of the body: if they be  also phenomena  of the
Soul, then is the Soul also, like the body, mate-
rial ; for it has properties in common.
  (b)  If  it be said the Soul may exist after the
body is dead and  decomposed, 1 reply, and the
soul may also not exist: one supposition is as good
as the other. Remember, it is not allowable in fair
                     B 
14
argument to take for granted the existence of a
thing,  merely because it may possibly exist.  If
you assert its existence, you  must prove your as-
sertion.  Jijffirmantis est probare: a posse ad esse
non valet consequentia.
  (c) If any one  shall say these properties are
only suspended for the time,  I would desire him
to examine what idea he annexes to  this suspen-
sion ;  whether it  be any thing more  or less than
that they are made not to exist for the time.   Ei-
ther no more is meant, or it is plainly opposed to
matter of fact. Moreover  if more be meant, it
may easily be proved  to  involve the archetypal
existence  of abstract ideas;  to  approach  to the
Platonic  absurdities  modified by the pre-esta-
blished  harmony  of  Leibnitz, which, I  appre-
hend, will not be  considered  as defensible at this
day.   It  can  also be shewn that such ulterior
meaning  will  contradict the  maxim impossibile
est idem esse et non esse.
  (d) If any one  shall say farther, " These men-
tal phenomena are not constituent parts, but acts
of the  soul, and  evidences of its existence; so
that the soul may continue to exist  when it  no
longer continues  to act, or  to act in this manner.
It does not follow that a  man's power of working
is annihilated because he has lost the tools or in-
struments with which he has usually workpcl,"—
I reply:  1.  That whenever the  evidences of the
existence of  a thing arise from the nature and
structure of the thing itself, they are synonymous
with its properties.  Such are the phenomena of
thinking with respect to the  Soul : they are con-
fessedly of its very essence.  I cannot give a
plainer illustration than  I have already given;
let my reader, if he be a mineralogist,  sit  down
and describe  a mineral; and  then let him sup-
pose all his characters annihilated.   2. As  these
intellectual phenomena  are  all  the evidences we
have of the Soul's existence, when these are de- 
15
stroyed  or  extinguished, so  is  the  conclusion
drawn from them.  When all the evidences of
the existence of life fail,  no one scruples to say
that life  itself is gone.  3. The instruments with
which a  man usually work, are only a small part
of, not all the evidences of his power  of working.
Were he to lose his senses, and his hands,  and
his powers of volition, and of voluntary motion,
which are also conjoint evidences of his power of
working, every one would say he had lost  that
power ;  that is, it no  longer  existed.  4.  It is
equally legitimate to assert of gold, for instance,
lhat what are termed its  essential and characte-
ristic properties are nothing more than acts  and
evidences of the existence of the substance gold,
which may  contiue to  exist, notwithstanding it
no longer continues to exhibit any of those phe-
nomena  which are termed its properties, but are
in fact only temporary evidences  of its existence.
Would  any reasonable  man  acknowledge  the
justness  of such an argument ?   5. If this  con-
clusion a posse ad esse—a pofentia  ad actum—
from the remotest of all possibilities of existence,
to actual existence, be  allowed—then can  any
thing whatever be proved to exist  in despite of
all proof to the contrary.  Would not a physician
regard that man as a lunatic, who was seriously
to say of a putrid dead body before  them ; " to be
sure, none of the actions which are the evidences
of life are exhibited at present, but  life may exist
notwithstanding ?"
  5.—(a) All relative terms imply the existence
of their  correlates : a  man  cannot be a father
without having a child, a husband without a wife,
&c.   Hence  when either  of two relatives cease
to exist,  the other does so likewise.
  (6) All those  ideas which make up  one idea of
the Soul, or in other words, all those properties
from whence we infer its existence, are relatives;
their  correlates  are ideas.  Thus, there can be 
16
 no.perception  without ideas to be perceived;  no
 recollection  without ideas to be remembered ;  no
judgment without ideas to be  compared ;  no vo-
 lition without  ideas  of the object on which it is
 exerted.
   (c) Locke has shewn that we have no  innate
 ideas; that all  our ideas are ideas of sensation or
 reflection ; and that the  ideas of reflection  are  no
 other than the operations of the mind on our ideas
 of sensation : that is,  all our ideas proceed  from,
 and are founded on the impressions made upon our
 senses.   The doctrine of the ancient school was
the same, nil unquamfuit in inlellectu, quod non
prius erat in sensu, which  is not  the less  true for
being acknowledged as true by the wisest men of
antiquity.*  I am aware of the " faculties  of the

  * That the best informed of modern writers hold the same doc-
trine,and that the whole phenomena termed mental arejjft.t rely
excitations of the nervous system perceived, I assert, on th* au-
thority ofCabanis, of Bichat, of Blum* nbach, of Richerand, of
Majendie ;as well as Hartley,Darwin,Priestley,and Lawrence.
The elementary works of Bichat, Richerand, Blumenbach, and
 Magendie, being usually read in all our medical schools, I sub-
join the references.
  See Bichat, Phys.  Res. (Dr. Watkins' Edit.  1809, Pliilad.)
p. 105,prope finem.  Richerand, (Dr. Chapman's Edit. 1813,
Philad.) p. 390—392 and p.400.  Blumenbach, (Dr. Caldwell's
Edit. 1795, Philad.) p. 195 of Vol. I.  Magendie, (Dr. Revere's
 Edit. Baltim. 1822,) p. 102, 103.
  The reader will find that the best informed and most approved
elementary writers on physiology  adopt the Latin axiom in the
text, verbatim, or in  substance.  So Haller, Phys. § 556, de-
scribes a sensation as an affection of the brain perceived. Prima?
Linese, Edinb. 1767.
  I strongly  suspect that no man is qualified to write on meta-
physics and the phenomena  of intellect, who is not well versed
in physiology, a branch of knowledge in which the Scotch school
of metaphysicians are  sadly deficient.
  I do not mean to  include Dr. T. Brown in this tirade against
his superficial and  dogmatic predecessors.  I agree with him,
that power and causation are words only,  and inseparable from
the real and actual  antecedents and consequents  to which they
 relate : and that our belief of the invariable attendance of like
 consequents on like antecedents, under like circumstances, is ra-
 ther intuitive than a process of  reasoning.  I much  fear, how-
 ever, he has not succeeded in obviaiing the difficulty  of Hume's
 argument against miracles;  for all that writer's argument an-> 
17
 mind," the numberless brood  of the  Scotch me-
 taphysicians.  I cannot and will not  condescend
 to reply to the dreadful nonsense on  this subject
 assumed as true by Dr. Reid and Dr. Beattie, or
 to the shallow sophisms of Dr.  Gregory, or the
 pages of inanity of Dr. Dugald  Stewart, or the
 ignorant hardihood of assertion of Dr. Barclay in
 his late inquiry.  We  are all before the public,
 and I am  content.  In  the mean  time,  let the
 reader ask himself, how he  could acquire ideas
 of  vision without the  eye and its apparatus—of
 odour without the  nostrils—of taste  without the
 papillae on the tongue and palate, &c.   Let him
 say what ideas a man could  have,  whose senses
 were entirely wanting.   This is enough.
   (d) But if all our ideas proceed from impression5-
 made on our senses, as these are entirely corpo-
 real, we never could have attained  ideas without
 the body;  that is, there would have been none of
 the phenomena of  perception, recollection, judg-
 ment, or volition without the body: that is, there
 would have been none  of those phenomena of
 thinking from whence we deduce the existence
 of  the Soul—none of the properties of the Soul,
 without the body: in other words, there would
 have been  no  Soul without  the  body.  So that
 the commencement of the existence  of the Soul
 depends on the commencement of the existence
 of the body.  Such is matter of fact.
  (e)  But the Immaterialists say, the  Soul is dis-
 tinct from  and independent of the body as to its
 existence : hence, it is both dependent and inde-
 pendent of the body:  that  is, it  does not exist,
 for contradictions cannot co-exist.

 plies to the introduction of new antecedents and of the usual and
 natural course of phenomena ; and the difficulty of establishing
 this introduction by testimony remains just as before. Dr. Browi.
 htm substituted one form of defence for another,  but he has not
 s lhstxntinlly altered the state of the case.  Brown, however, is
a eleir sighted and able metaphysician.
B 2 
IS
The Immortality, a parte ante, of the Soul being
  null, let us examine its  Immortality a parte
  post.

  (a)  All impressions made on our senses can be
traced up to  the  internal  sentient extremity of
the nerve impressed, and no further.
  (6)  When an impression has been made on our
senses by means of external objects, we have  the
property of perceiving the  effect of that impres-
sion at a distance  of time,  and after the original
impression has ceased.  This is memory and  re-
collection.  Hence, although all  our ideas have
been caused by impressions made on our senses
originally, we may lose one or two of our senses,
and yet remember the ideas which are the effect
of the impressions formerly made on them.
  (c)  But ideas  can  no  more  be remembered
without the nervous system, than they could have
been caused originally without the senses.  All
this is plain matter of fact.
  (d) At death, however, not only all our senses
are destroyed, (the only sources of original ideas)
but the nervous system itself is destroyed, which
is the sine qua non to the existence  of ideas al-
ready caused.  At death, therefore, all our ideas
of every kind are destroyed.
  (e)  But there can be none of the properties of
the Soul without ideas; for these are relates and
correlates ; and if all  the  properties of the Soul
are destroyed, the Soul itself is destroyed.
   (/) Therefore, whatever may be the case dur-
ing the life  of the body, the Soul did not exist
previous thereto, and  is destroyed when that is
destroyed.
   (g) And when it is considered that many cir-
cumstances  during the life of the body may to-
tally destroy  for a time all the properties of  the
Soul, the little of existence that remains is hard-
ly worth contending for. 
ib
  (h) But when it is further considered, that the
natural immortality of the Soul is supposed a ne-
cessary consequence of its immateriality, it will
be a necessary consequence that this  immaterial
soul does not exist at all.
  6. If the Soul exist at all, it must exist some-
where, for it is impossible to frame to one's self
an  idea  of any thing existing  which exists no
where, and yet whose operations are limited as
to space.
  (6) But if the  Soul exist somewhere, by the
terms it occupies space ; and therefore is extend-
ed ; and therefore has figure or shape, in com-
mon with matter
  (c) Moreover by the supposition of every  Im-
materialist  (except Malbranche,  Leibnitz,  and
Berkely) the  Soul  acts upon the bofly ; that is
upon matter.   That  is, it attracts and  repels,
and is attracted and repelled ; for  there  is  no
conceivable affection  of  matter, but  what is
founded upon, and reducible  to, attraction  and
repulsion.   If it be attracted and repelled, its
re-action must be  attraction and repulsion.  This
implies solidity.
  (d)  The Soul then possesses extension, figure,
solidity, attraction,  repulsion.  But  these com-
prise all the properties by which matter is cha-
racterized, and the Soul therefore, whatever else
it be, is a material being.
  (e) But it cannot be both  material and imma-
terial at the same  time, and therefore it does not
exist.
  7. Those truths which we derive from the evi-
dence of our senses,  carefully observed and suf-
ficiently repeated, are more weighty than  such
as  are mere deductions of reason and argument.
If I feel that by beating a large stone  with my
fist  I  shall  hurt my knuckles, I cannot doubt of
that, after a sufficient number of trials.   If I find
that a large quantity of strong wine will render 
20
 me intoxicated, I cannot disbelieve the result of
 experience.  I see that the mental  phenomena
 are connected with the organization of the human
 body, by means of the  nervous apparatus  which
 is a part of it.  I know by observation and expe-
 rience that if you destroy that part of the ner-
 vous system which supplies any one of the organs
 of sense, as the optic nerve of the eye, the or-
 gans of that sense no longer supply me with the
 same feelings as  before.  All this  is  matter of
 fact,  ascertainable in the same way that we as-
 certain the effect of a bottle of Madeira ; by  the
 use of our senses.  About all  this we can no
 more doubt, than about our existence.  But what
 evidence can we  possibly have of the existence
 of  the Soul.  It is not cognizable by any of our
 senses—by* any of the common inlets of know-
 ledge—it  is, by  the hypothesis, immaterial, it
 hath  no  relation to matter.  By the  very nature
 of it, we can have  no sensible proof of its exis-
 tence.  It  is an  hypothesis, a  supposed  being,
 introduced to account for appearances manifestly
 connected  with our bodily organs, and which, so
 far as we know, cannot take place without them,
 whether there be  a soul or not.   This connexion
 we see,  hear, feel,  and know  to exist, though
 we do not  exactly know how  to trace it.   But
 the Soul  has no existence for our senses—it is a
 being whose  existence  is assumed  because  the
 present state of knowledge  does not  enable us
 (perhaps) to account for the precise mode of con-
 nexion between  intelligence and our nervous
 system.  I  shall  by and bye shew, that we are
just as much at a loss to account for the life of a
 tree, as for the reasoning of an animal.
  But let the reader reflect for a moment, and
 ask himself,  if this hypothetical  introduction of
 an  immaterial soul  to solve the difficulties (hat
 our ignorance produces, be not a manifest breach
 of the acknowledged axiom, a posse ad esse non 
SI
valet  consequential  A mere refuge for present
ignorance of a connexion which future  know-
ledge may unravel.
   A theory explains unknown facts by the laws
and properties of known facts.  Newton applied
the cause  which makes a stone fall to the earth
to the tendency of the planets  toward the sun.
Here was nothing new assumed to  aid the rea-
soning.   Had he said that as it was impossible to
explain  the tendency of the  planets  toward the
sun,  by any properties  of  the planets  or  the
sun, and therefore it must be owing to some an-
gel whose duty  it was  to  impel the planets in
their  proper direction,  this would have been hy-
pothesis : just like our notions of the Soul to ac-
count for the phenomena of the body.
   So  that we not only have  no direct and satis-
factory  evidence of the existence of the Soul, and
from  the presumed nature of it never can have,
but the  clear, direct, undeniable evidence of our
senses is all the other way.
   "I  see" (says Mr. Hallet, in his  discourses)
"a man move, and hear him speak  for some
years.  From his speech, I certainly infer that he
thinks as I do.   I  see, then,  that man is a being
who thinks and acts.  After  some time, the man
falls down in my sight, grows cold and  stiff.  He
speaks and acts no more.  As  the only reason  I
had to believe that he did think, was his motion
and speech, so now that  they cease,  I  have lost
the only way I had of proving that  he had the
power of thought.  Upon this  sudden death, the
one visible thing, the one man  is greatly  chang-
ed.  Whence could I infer that the same he con-
sists of two parts, and that the inward part  con-
tinues to live and think, and flies away from the
body, while the outward part ceases to live and
move  ?  It looks as if  the whole man was gone,
and that all his powers cease at the  same time.
So far as I can  discern, his motion and thought
die together. 
22
  " The powers of thought, speech, and motion
equally depend on the body, and run the same fate
in case of men's declining old age.   When a man
dies through old  age, I see his  powers of motion
and thought decay and die together, and each of
them by degrees :*  the  moment  he ceases  to
move and breathe, he appears to cease  to  think
too.
  *' When I am left  to mere  reason, it  seems to
me, that my power of thought as much depends
on my body, as my  power of sight and hearing.
I could  not  think  in infancy. My powers of
thought, of sight, and of feeling are equally lia-
ble  to be obstructed  by the body.   A blow on the
head has deprived a man of thought, who  could
yet see, and feel, and move.   So that naturally
the power  of thinking seems to belong as much
to the body, as any power of  men  whatsoever.
Naturally there appears  no more reason to sup-
pose a man can think out  of the body than that
he can hear sounds or feel cold out of the body."
  If this be the case (which cannot be denied)—
if there neither be in fact, nor from the nature of
the thing ever  can  be, any direct  evidence for
the existence of an immaterial,  distinct, indepen-
dent soul—still further, if all the direct and po-
sitive evidence that  there  can be of any thing
whatever, all that the present case can in the na-
ture of it admit, is against the existence of such
a soul—how strong,  how absolutely irrefragable,
how evident ought that reasoning to be, by which
its  existence  is inferred !  Even  the possibility
of  its being fairly  and  honestly  disputed, is a
strong  presumption  against its conclusiveness.
Who can fairly and honestly dispute the depen-
 dance of thought on the  body ?
   8. I apprehend all the phenomena termed men-
 tal or intellectual, are explicable  as  phenomena

  • The reader will recollect Gil Bias' \rchbishop of Toledo. 
33
of the body.  Hartley,  and Destut Tracey, the
one in his first volume on Man, and the other in
his Ideologic have done it to my satisfaction.  I
cannot  enter  into their reasonings;  they must
speak  for themselves.  The public by and bye
will give to these authors that fair play which the
orthodoxy  of  the moment will  not  concede to
them.
   9. We have not the slightest proof of any kind
that ideas can arise or can  exist independently
of corporeal organization. We have never known
them  so to  exist.   We know not, nor have we
from  facts,  the  slightest  reason to believe that
they can.   But the Soul itself has  been invented
to account  for them.  They are (by  those who
believe in a separate  >>ou\)  considered as essen-
tial to that being—the peculiar property and re-
sult of the  Soul's operations.  But where is the
proof that ideas can exist in the Soul without the
body ?  Where  is thought when the body dies ?
Where was thought before the body began to ex-
ist?  De non  apparentibus et non existentibus ea-
dem est ratio.   All assertions are equally true
concerning  that which doth not exist, and that
of whose existence there is  no evidence.
   Sucli are  the arguments of an abstract and me-
taphysical nature, on  which I ground my opinion
that an immaterial, immortal soul, separate from
the body, does not and cannot exist:  and it ap-
pears to me, from what has been said, that there
is the same proof for  the  truth of the doctrine of
Materialism, as  that gold is heavy,ink black, wa-
ter fluid, or any other indubitable assertion.  Also
that there  is  the same  proof that the opposite
doctrine ca mot be true, as that contradictory as-
sertions cannot be both true.

   I come now to a class of arguments that as-
sume a physiological  rather than a metaphysical
character.   But before I enter upon this branch 
2<h
 of the subject, I beg leave to state some physiolo-
 gical propositions relating  to the animal system,
 that bear upon the subject in question.
   The objects around us have been conveniently
 classed into the mineral, vegetable,  and animal
 kingdoms.  The particles of the bodies whereof
 each kind of substance is composed, have peculiar
 active properties; by which  they  arrange them-
 selves, when free  from the obstacle of pressure
 by foreign bodies, into some peculiar form.
  The particles of a mineral substance, when
 they  have full time and  room to arrange  them-
 selves according to their respective propensities,
 assume  certain  figures,  usually  prismatic;  of
 which the number  of sides, and size of the angles
 are determined within certain limits by the che-
 mical constitution of the mineral in question.
 Hence, the determination of mineralogical species
has,  within these  twenty years, been  made to
rest on the form of the  crystal, particularly  by
 all the mineralogists of the French school.  The
 general  fact is indubitable;  but  the  limitations
 and the precise relations between chemical com-
 position and the figure  of the mineral nucleus,
 have  not yet been accurately determined.
  Minerals increase in size by the crystallization
 of adventitious particles  round a crystallized nu-
 cleus, producing secondary  forms ;  but  they do
 not  devour,  decompose,  digest,  assimilate, se-
 crete, excrete, grow,  and propagate.  They  do
 not seem to have any  property to which the term
 life can  fairly be  applied, or to suffer any thing
 like  what  we call  death;  although it is impossi-
 ble to doubt that they are endowed with  active
 properties.  Like  all  other  substances, they are
 liable to chemical decomposition, and  consequent
 disintegration.  They are utterly devoid of sen-
 sation and volition ; and have no apparatus con-
 necting them  with surrounding bodies.
   Vegctab.es are substances  that have a peculiar 
25
organization or arrangement of solid, tubular, cel-
lular, and  fluid parts: by means of which tHfey
feed,  digest,  assimilate, secrete, excrete, grow,
and propagate their kind.  They die of violence,
of disease,  of old age.  They are not locomotive,
being fixed by their roots. No nervous apparatus
has hitherto been discovered in them ; but certain
of their fibres are irritable and contractile. Hav-
ing no  nervous apparatus, they have no percep-
tion (sensation,) or volition ; they do not think.
No vegetable has hitherto been clearly ascertain-
ed to appear, but as the offspring of a former ve-
getable : and though, by process of assimilation,
inorganic and  lifeless matter is converted into
organic and living matter, the vegetable life (so
far  as we know) must pre-exist.   The chief use
of vegetables seems to  be the furnishing of food
for  animals, and partially preparing lifeless and
inorganic matter to become sentient and capable
of pain  and pleasure.   With the exception of less
than one part by weight in a thousand, vegetables
are  resolvable  into  carbon,  hydrogen, oxygen,
with a small  portion  of nitrogen, potassium, and
phosphorus.  The earths found in them do not
seem to be essential to their composition.
  Animals are  substances that have a peculiar
organization or arrangement of  solid, tubular,
cellular, and fluid parts; by means whereof, they
devour, digest, assimilate, grow, secrete, excrete,
and propagate.  They die of violence, of disease,
of old age.   When dead, they  are decomposed
into azote or  nitrogen, carbon, hydrogen,  oxy-
gen,  lime, and  phosphorus.   They are locomo-
tive.  They have a muscular apparatus for that
purpose ; and they have  a  nervous apparatus for
the purposes of sensation and volition,  by which
they are connected with  surrounding objects ani-
mate and inanimate.  By assimilation, they con-
vert inorganic  and lifeless  into organic, living,
and sentient  matter.  It has not yet been clea. - 
26
ly shewn, that any animal has arisen unless as
successor to some similar animal, his immediate
progenitor.  The  nisus  formativus of  Blumen-
bach,'the  theories of Darwin and La Marck, are
not impossible,  but have as yet few converts.
The doctrine of equivocal  generation  seems to
have the weight  of fact against it.   The Zoophy-
tic animals, the  animalculse infurosiee, the worms
and  other parasites that prey  on the internal
parts of living animals, form difficulties, but no
exceptions; just as the  vegetable efflorescences,
the mosses, the confervse, and other minute vege-
tations do in Phytoiogy.
  Every vertebrous animal has  (a) an organic
system  destined to support the mere life  of the
animal, and which is analogous  to  the organic
system  of a vegetable:  (b) a muscular system
destined in part for internal action, in part for
locomotion ; (c)  a nervous system, in  part sub-
servient peculiarly  to organic and muscular life,
and  in  part subservient  peculiarly to  sensation
and volition.
  The involuntary muscles possess, by means of
secretion supplied by the organic system and the
nervous apparatus appropriated to it, a power of
contraction, or of becoming thicker and shorter,
on the application of stimulus.  Stimulus may be
either  the natural stimulus  of the nervous sys-
tem, or of the  blood, or it may be artificial.   The
actions  of the  involuntary muscles go on, without
being felt or perceived.   The voluntary muscles
are stimulated naturally by that portion  of the
nervous system  whkh is appropriated to  sensa-
tion  and volition.   Galvanic processes have to a
certain  degree been found  a substitute for the
nervous stimulus of the muscles, voluntary and
involuntary.
  It  has  been  ascertained, that the muscular
power resides in the muscles, and is a property
of the muscular fibre, and  is distinct from the 
21
nervous power, which acts merely as a stimulus
to muscular irritability.  It  has been ascertain-
ed that the nervous  power destined to the pur-
poses of involuntary,  insentient,  organic  life, is
distinct from the nervous power destined to  the
purposes of sensation and volition ;  for each can
be shewn  separate  from the other.  It has been
made highly probable, that the first mentioned
portion of the nervous system is  confined to  the
medulla oblongata and the ganglionic  plexuses:
the latter and more important portion,  to  the
brain as its centre.
   I am aware of Dr. Ferriar's collection of cases
in the Manchester Transactions ; of Sir Everard
Home's collection of cases  in  the Philosophical
Transactions ; and of many other cases  not in-
cluded in the  papers  of  these  gentlemen, where
lesions of the  brain have ocurred without much
apparent  injury to intellect.  No physiologist re-
gards them as weighing a feather against the sup-
position of the brain being the  centre of the ner-
vous  system appropriated to sensation and voli-
tion : tor we  do not yet know,  by experiment,
what portions of the brain are exclusively so ;
nor is a general fact  established  by induction of
innumerable particulars, to  be  set aside,  on  ac-
count of a few apparent anomalies of difficult ex-
planation.  The  theory comprises those parts of
the brain that are essential to sensation and vo-
lition ; and not  the  more bulky mass which ap-
pears merely  as  a subservient  envelope.  The
experiments of Sir Everard  Home on the connex-
ion of memory with  the cortical  substance,  and
 the more important " Researches"  of  M. Flo'i-
rens, promise  to  throw light on this difficult sub-
ject,  which only requires patient  and pursued in-
vestigation.   Some  internal sentient extremity
 there must be to each main branch of  the nerves
of the senses.  In relation  to  the present inqui- 
28
 ry, place it where you please, or where the best
 settled facts point out.
   The above views that I have taken of the mi-
 neral, vegetable, and animal economy,  I  offer to
 the reader not as any deductions  of theory, but
 as expressions of separated and ascertained fact,
 which a well read modern physiologist will hard-
 ly venture  to  gainsay, under  the limitations  I
 have  used in stating  them.  I  refer to Bichat,
 Richerand,  Magendie, Dr. Wilson  Philips, Sir
 Everard Home, and the  Phvsical  Researches of
 M. Flourens in p. 299 of vol xx. of Ann.de Chim.
  I proceed to my second class of arguments.
  1. The  propensity of the minute  particles  of
 quartz to  unite together in a six-sided prism ter-
 minated by  six-sided  pyramids—of the  zirconite
 to assume a tetrahedral prism terminated by te-
 trahedral  pyramids—of the diamond and garnet
 to appear as  dodecahedrons—of pyrites as a
 cube—of  carbonate of lime as  a  rhomboid, &c.
 &c. so that  their  particles  seek  out an union
 with adjacent particles, not  indiscriminate  and
 promiscuous, but in the peculiar manner proper
 to form these figures—is either  a property of the
 material particles themselves, or it  is  owing to
 some  separate being or principle who impresses
 on the particles the necessary force  in the  ne-
 cessary direction on each occasion.  No one hi-
 therto, however, has thought of ascribing this  pro-
 pensity but to some property belonging and  es-
 sential to  the particles themselves.
  The arrangement of the nutritious matter ta-
 ken in by  a  vegetable, in the peculiar form which
that vegetable affects, and by which  it is charac-
 terized, has usually been attributed to the effect
of vegetable life as connected with vegetable or-
ganization.  No one  hitherto has  advanced  the
hypothesis of a vegetable Soul—distinct from the
 plant, but regulating and  governing it—a being 
29
superior to, and surviving, the  vegetable.  Yet
there is no more  difficulty in  supposing percep-
tion a property of a nervous system, than vitality
a property of a vegetable system.  We see them
both, like other properties, intimately and  essen-
tially connected, as antecedents and consequents,
with the subject to which they are referred; and
we refer them accordingly, as in all other cases
of similar connexion.  How is life of any kind
the result of mere matter and motion ?
   We see in the human frame a nervous appara-
tus that is  essentially connected with  sensation
and volition, from which these properties arise—
that serves no other purpose than to give birth
to them—we see  them in infancy in a state ap-
proaching to nonentity; forming gradually and
slowly ; growing with the growth of the being to
which they belong,  and improving by degrees—
we see  them vary in kind and intensity accord-
ing to our education, and the nature of the society
in which we are thrown—we see them dependant
for all their characters on the manner in which
that part of our nervous system is excited  ab ex-
tra ; so  that a man  born and educated in Con-
stantinople will have one set  of impressions, one
habit of sensation and volition, and a man with a
similar  arrangement of nervous apparatus born
and educated among the Quakers at Philadelphia
will have another.  All this  is the result  of ge-
nerating causes extraneous to the system—ow-
ing to specific peculiarities of  excitement  that
causes the nervous apparatus to  act in  this man-
ner rather than in that, and to assume different
habits.  1 say, we see all this  to be in every case,
undeniable  matter  of  fact.   How then can we
deny sensation and volition to be the result of
the stimulated nervous system  ?  There  is the
same connexion of phenomena, the same uniform
result of that connexion,  presenting  no more
difficulty in  the  case  of sensation and volition,
                     c 2 
30
than in the case of glandular secretion and ani-
mal  heats; or  muscular motion;  or sanguifica-
tion ; or the secretion of resin in  the pine, and
sugar in the maple from the same introsuscepted
fluid.  All the processes  are equally inexplica-
ble from any a priori arrangement of matter and
motion ; all of them stand in equal  need for ex-
planation of an immaterial principle; for although
we see clearly  that  these are the phenomena of
organized matter in each case, yet in no case can
we explain the rationale  by any of the known
properties of other inorganized matter.   Hence,
according to the psychological doctrines, we must
resort to  some  distinct and superadded being;
to the anima intellectualis ; the anima sensitiva
and the anima vitalis of the ancients,—or to the
separate faculties of the Scotch  school of meta-
physics, a species  of entities  most  accommoda-
ting, ready for all  work, and always in waiting—
or to the  equally unintelligible arrangement of
Dr. Gall's cramology—or  to some being of ana-
logous existence to the immaterial Soul of the or-
thodox.  For I  assert,  and  appeal  to matter of
fact, that,
   There is exactly the same evidence that sensa-
tion  or perception  and volition are properties  of
the nervous  apparatus of the human  system, that
there is of contractility being a properly of mus-
cular fibre, or polarity the property of a particle of
pyrites or a particle of light.
   On the  truth of this proposition, I should (were
it necessary) be willing to rest the controversy.
In the one case and the other, constant concomi-
tance is the sole foundation for ascribing neces-
sary  connexion.   If it  be sufficient in any one
of the cases, it ;.s  sufficient in all.   It is not ne-
cessary that  we should be  able to explain the
quomodo: it is enough that our senses, under
careful observation, assure us of the fact.  Fu-
ture facts and  the future improvement of the hu- 
31
-nan intellect will enable our posterity to do that
which our more imperfect knowledge will not en-
able us  to accomplish : just as the present gene-
ration are able to explain what remained an en-
igma to their forefathers.
  2. I have said above, that our perception, voli-
tion, and in  fact our other  intellectual faculties,
begin from  nothing in  infancy,  grow with our
growth, improve with our experience, vary with
our education,  and differ,  not merely as to the
nervous systems  excited, but in  consequence of
the  habitual  difference  in the stimuli applied.
Suppose the original  intellect of  two infants ex-
actly the same; educate one among the thieves
of broad  St. Giles in  London,  and the other
among the best class of Philadelphian Quakers,
would  their  intellect be the  same  at  one  and
twenty ?  But  is the Soul thus  mouldable  and
changeable ?  Is the Soul infantile as well as the
body ?
  3. If the intellectual phenomena depended en-
tirely on the Soul,  then we should be unable to
produce, annihilate, alter, or modify them by any
mere mode of action operating merely on the bo-
dy.  But                  *      J
  Our  ideas are frequently produced and  com-
monly  modified by the internal state of our bo-
dily organs—by the state and condition of our
organic life: hence the  phenomena of dreaming,
of delirium, and the hallucinations of hypochon-
dria; and the alterations produced in our sensa-
tions and ideas by our state of  internal health.
Our ideas also are produced and modified by sub-
stances exhibited to us acting medicinally; as by
wine, by  opium, by cantharides, &c.   But as
Judge Cooper has said in his  Medical Jurispru-
dence, how can you exhibit a dose of glauber's
salts to the Soul ?
  If then sensations, ideas, reasonings, and vo- 
32
 litions, are produced,  modified, or extinguished,
 by the condition of  the involuntary parts of our
 organic  system—by  disease—by  medicine :  if
 they be (as we know they are) greatly under the
 command  of the physician  who acts only on the
 body—are  not  these  effects thus produced by
 means of  the body, bodily  effects ?   What has
 the Soul to do with them ?  Are not these effects,
 however the only evidences  of the Soul's exis-
 tence—the essential, incommunicable properties
 of the Soul,  according  to  the Immaterialists ?
 Yet are they manifestly  produced on the body;
 and  so far  as we  can see, on the body alone, by
 means of material stimuli calculated to act sole-
 ly on the body ?
  If it be said, the body  is no more than the in-
 strument of the Soul, which  can only act  accord-
 ing to the condition of  that body with which it is
 connected, and when the body is altered, the in-
 tellectual  phenomena which  it is  calculated to
 exhibit, are altered also—then it follows, from  the
 evidences of what takes place, that the very nature
 of the Soul is  altered by  altering  the  condition
 of the body, and the Soul therefore is under  the
 control of accident, of  disease, of medicine, and
 may be just what a physician chooses to make it.
 For  if a physician can  control the intellectual
 phenomena of sensation,  memory, judgment, and
 volition,  (as he  can) then are all  the essential
 properties of the  Soul  itself  subject to the arti-
cles of the Materia Medica, and slaves of  the
 Pharmacopeia.
  4.  I have already said, that no phenomena of
mere matter and  motion—no principle of mecha-
nical or chemical philosophy  can account for  the
 phenomena of life and stimulus—for digestion,
assimilation, secretion.   These are just as diffi-
 cult as sensation, memory, or volition :  the inter-
 position of an immaterial Soul is as necessary to 
33
 vegetable life, as to the human faculties.   If this
 be  denied,  shew me where and  by whom they
 have been explained, or explain them if you can.
  5.  I appeal  to  any physician  accustomed to
 cases of insanity ; and I ask whether all the  in-
 tellectual appearances in that disease are not ma-
 nifestly the result of the morbid  state of the bo-
 dily organs ?  Is not this the case from the most
 violent symptoms of mania, to that almost imper-
 ceptible obliquity, from which in some degree or
 other, hardly any of us are free.   In fact, such as
 is the state of  our system, such are the mental
 phenomena  we  exhibit:  the latter are the result
 of the former.  Can you  put a male mind into a
 female body, or vice versa ?  Let a parent de-
 cide this question ; he will answer at once, No.
 Can you put an old  head  on young shoulders ?
 No.
  6.  But  there are no mental phenomena exhi-
 bited by the human species  that are  not also ex-
 hibited by the brute species.  The  difference is
 concomitant with difference of organization. The
 superiority of the human being  arises from  his
 erect position, from  the  skill  with which he can
 use  his hands, and  from the faculty of  speech.
 These give rise  to the manipulations of art, and
 to the preservation  and propagation of  know-
 ledge.  For  want  of these, one generation of
 brutes is little wiser than the preceding.   There
 is with them no means of accumulating  know-
 ledge.  When a dog has  lost his master, does he
not seek him at  the  places  his master has been
accustomed  to frequent ?  I know by oft repeat-
ed facts in my own case,  that he does.  Does not
this imply memory, ratiocination, volition ?  So
many volumes of instances of the sagacity of ani-
mals, particularly of the canine species,  have
been collected, and instances are so familiar, that
I would not condescend to argue with a man who
would have hardihood enough to deny it.  All 
31
these are intellectual phenomena of the same kind
with such as we exhibit; the difference is in com-
plication and degree only.   They are evidences
therefore of  an  immaterial, jmmortal,  distinct
Soul, producing them.  What say you to the im-
mortal Soul of an opossum or an oyster?
  I see no  possibility of denying  the facts, or
avoiding the conclusions; and I leave the diffi-
culty to be  overcome by those who  choose volun-
tarily to encounter it.
  The Christian  finds no  difficulty in  it.  He
says,  that  by nature, all  animals, human  and
brute, die and return to the dust they are made
of: but God  has been  pleased, through  Jesus
Christ, to promise a future state of rewards  and
punishments, and a  future immortality to human
beings.  Hence,  to  the  Christian, who has  no
evidence but the  Scriptures  for this, those sacred
writings are of inestimable value.
  Finally,  I  say, that  the  phenomena termed
mental, have  been so well explained by Hartley,
Cabanis, and  Destut Tracey, that no  man con-
versant with their writings, can hesitate to allow
this.  I say it is  not possible for a fair man, con-
versant with physiology, to deny, that a sensa-
tion from recent impression, and an idea from re-
collection,  are motions in the  brain (or common
sensory) perceived.   As all our intellectual phe-
nomena consist of sensations or ideas, which are
the materials and  substrata of memory, judg-
ment, and volition, all of them consist in motions
communicated to the corporeal  nervous  system
-—to the common sensory ; whether  by external
impression, by association,  or  by  internal sym-
pathetic action.  They are therefore corporeal
phenomena,  and no more.  Destut  Tracey has
shewn this so clearly, and so well explained the
phenomena of memory, judgment, desire,  voli-
tion, as mere names given  to various states and
conditions of our brain, that I do not expect any 
rVj
refutation will or can be given to the view of the
subject he has taken.  Orthodoxy is in  the  seat
of authority now, but truth will prevail at last.
   In speaking of the brain as the common  sen-
sory,  I speak  according  to the language of all
physiologists of repute, who seem  not to be sha-
ken by the anomalous cases to the contrary.  Fer-
riar's collection is good for little, because his au-
thorities are sometimes deficient in accuracy of
observation, and sometimes in credibility.  But
whether the internal sentient extremities of the
sensorial nerves  terminate in the brajn or else-
where,  is of no moment whatever  to the argu-
ment;  they must terminate  somewhere;  and
where they do terminate, is, for  my  purpose,
equivalent to the brain ;  and this word may be
used  for the sensorium, wherever that may be.
   In  arranging the preceding arguments, facts
are repeated ;  but the point of view in which
they are placed, authorises me as I have thought,
to distribute them under distinct heads.
   I know  the  obloquy to which Mr. Lawrence,
the surgeon, has been exposed, in consequence of
his having advanced the  opinion of the materia-
lity of the Soul, or rather the singleness of hu-
man nature as consisting of the organized body
only;  but the  obloquy that results from clerical
persecution, popular bigotry,  and  professional
jealousy cannot detract from the reasoning  of a
man on all hands confessed to be among the most
able and best informed anatomists  and physiolo-
gists of the day.  I  give therefore the following
extract copied with some few  omissions and un-
important  alterations  from his lecture on  the
Functions of the Brain.  Mr. Lawrence's book
has been widely disseminated  in England ; but it
is comparatively unknown in the United States;
for not one bookseller in the  Union is hardy
enough to  publish  it!  Such is the  state of the
press in this country of boasted  freedom,  and 
36
 such the tyranny exercised by the orthodox cler-
 gy over  the minds of the people !   A tyranny
 that I have a right to  exclaim against, because I
 feel it, for  I  know  of no bookseller who would
 put his name to this pamphlet:—
   "There would be little inducement to compare
 together the various animal structures, to follow
 any apparatus through the whole animal series,
 unless the structure were  a  measure and crite-
 rion of the  function.   Just  in the same propor-
 tion as organization is reduced, life is reduced :
 exactly as  the organic parts are diminished in
 number and simplified, the vital phenomena be-
 come fewer and more simple; and each function
 ends when the respective  organ ceases.  This is
 true throughout zoology : there is no exception in
 behalf of any vital manifestations.
  "The same kind of facts, the same reasoning,
 the same sort of evidence  altogether, which shew
 digestion to be the function of the alimentary ca-
 nal,  motion to be the function of the muscles, the
 various secretions of their respective glands—
 prove that sensation, perception,  memory, judg-
 ment, reasoning, thought,  in a word, all the ma-
 nifestations called mental  or intellectual, are the
 animal functions of their appropriate organic ap-
 paratus, the central organ  of" the nervous system.
 No difficulty or obscurity  attends the latter case,
 which does not equally affect all  the former in-
 stances :  no kind of evidence connects the living
 process with the material  instruments in the one,
 which does not apply just  as clearly and forcibly
 to Ihe other.
  " Shall I be told that thought is  inconsistent
 willi  matter; that we cannot  conceive  how  me-
 dullary substance can perceive, remember, judge,
 reason ?   I acknowledge  we are  entirely igno-
rant  how the parts of the brain accomplish these
purposes; we know only the fact:  we are equally
ignorant  how the liver secretes  bile, how the 
o7
muscles contract, or how any other living purpose
is effected : and so we are how heavy bodies arc
attracted  to the earth, how iron is drawn  to the
magnet, or how two salts decompose each other.
Experience is, in all these cases, our sole, if not
sufficient  instructress, and the constant conjunc-
tion of phenomena, as exhibited  in  her lessons,
is the sole ground for affirming a necessary con-
nexion between them.   If we go beyond this, and
come to inquire the manner how—and attempt
to discover the mechanism by which these things
are effected, we shall find every thing around us
equally mysterious,  equally incomprehensible :
from the stone which falls to the earth to the co-
met traversing the heavens—from the thread at-
tracted by amber or sealing wax to the revolu-
tions of planets in their orbits—from the forma-
tion of a  mite in  cheese, or a maggot in  putrid
flesh, to the production of a Newton or a Frank-
lin.
   "In opposition to these views, it has been con-
tended, that thought is not  an  act of the brain,
but  of an immaterial substance,  residing  in, or
connected with it.  This large and curious struc-
ture, which, in the  human subject, receives one-
fifth of all the blood  sent  out  from the heart;
which is so  delicately  and  peculiarly organized,
so  nicely enveloped  in successive  membranes,
and securely lodged in a solid  bony case, is by
this supposition left  almost without an office:
being barely allowed  to be capable of sensation.
It has indeed  (under this hypothesis) the easiest
lot in  the animal  economy ; it  is better  fed,
clothed, and lodged than any other part, and has
less to do.  But its office (only one remove from
a sinecure) is  not a very honourable one:  it is a
kind of porter, instructed to open the door, and
introduce  new comers to the master of the house,
who takes on himself the entire charge of receiv-
ing, entertaining, and employing them. 
38
    " Let  us survey the natural history of the hu-
 man mind—its rise, progress, various fates, and
 decay—and then judge whether these accord best
 with the hypothesis of an  immaterial agent,  or
 with the  plain dictates of common sense, and the
 obvious  analogy of every other organ and func-
 tion, throughout the  boundless  extent of living
 beings.
   " But you must bring to this physiological ques-
 tion, a sincere  and earnest love of truth : dismis-
 sing  from your minds all  the  prejudices  and
 alarms which have been so industriously connect-
 ed  with it.  If you enter on this inquiry in the
 spirit of the bigot and  the  partisan—suffering a
 cloud of fears and hopes, desires and aversions,
 to hang round your understandings, you will ne-
 ver discern objects clearly ; their colours, shapes,
 and dimensions, will be confused, distorted, and
 obscured by the intellectual mist.  Our business
 is to inquire what is true, not which is the finest
 theory—not what will  supply the  best topics of
 pretty composition  and elegant declamation ad-
 dressed to the prejudices, passions, and ignorance
 of our hearers.   We need not fear the result of
 investigation :  reason and free  inquiry are the
 only effectual antidotes of error.  Give them full
 scope, and they will uphold the truth, by bringing
false opinions,  and all  the  spurious offspring of
ignorance, prejudice, and  self  interest,  before
their severe tribunal,  and subjecting them to the
test of close examination.  Error alone needs ar-
tificial support; truth can stand by itself.
  " Sir Everard Home, with  the assistance of Mr.
Bauer and his microscope,has shewn us a man eight
days old  from the time of conception: about as
broad and a little longer than a pin's head.  He sa-
 tisfied himself that the brain of this homunculus
 was discernible. Could the immaterial mind have
 been connected with it at this time ?  Or was the
 tenement too small even for so etherial a lodger? 
39
Even at the full period  of utero-gestation, it is
still  difficult to trace any vestiges of mind; and
the believers in its  separate existence have left
us quite in the dark  on the precise time when
they suppose this union of Soul and body to take
place.  Some endeavour to account for the entire
absence of mental phenomena at the time of birth
by the senses and brain not having been yet call-
ed into action, by the impressions of external ob-
jects.  The senses and brain begin to be  exer-
cised as soon as the child is born ; and  a  faint
glimmering of mind  is dimly perceived in the
course of the first months of existence; but it is
as weak and infantile as the body.
  " As the senses acquire their powers, and the
cerebral mass becomes firmer, the mind gradual-
ly strengthens,  advances slowly with the  body
through childhood to puberty, and becomes  adult
when the development of the frame is complete ;
it is, moreover, male and female, according to
the  sex  of the body.  (The  propensities, the
modes of thinking and acting, are  manifestly in-
fluenced by sex.)  In the  perfect period of  orga-
nization, the mind is seen in the plenitude  of its
powers ; but this state  of full vigour is short in
duration, both for the intellect and the corporeal
fabric.  The wear and  tear of the latter is evi-
denced in its mental  movements : with the de-
cline of organization  the mind decays; it he-
roines decrepit with the body; and, both the one
and  the other are,  at the same  moment, extin-
guished by death.
  " What can we infer from this  succession of
phenomena ? The existence and action of a prin-
ciple entirely distinct from the body ? Or a  close
analogy to  the history of all other  organs and
functions ?
  " The number and kind of the intellectual phe-
nomena in  different  animals, appear to  corres-
pond closely to the degree of development of the 
40
 brain.  The mind (mental  or  intellectual facul-
 ties)  of the Negro, Hottentot,  Calmuck, "and Ca-
 iib, is inferior to that of the European ; and their
 organization also is less perfect.  The large cra-
 nium and high forehead  of the ourang-outang lift
him above  his brother monkeys; but the develop-
 ment of his cerebral hemispheres,  and his mental
 manifestations,  are  both equally  below those of
 the Negro.   The gradation of organization  and
 of mind passes  through the monkey, dog, ele-
 phant, horse, to other  quadrupeds :  thence  to
 birds, reptiles, and fishes ; and so  on to the low-
 est links of the animal chain.*
  " In ascending these steps of one ladder, fol-
 lowing in regular succession at equal  intervals,
where shall we find the boundary of  unassisted
organization ? Where place the beginning of the
immaterial principle called in aid ?  In that view
which assimilates the functions of the brain  to
 those of other organic parts, this case has no dif-
ficulty.  As the structure  of  the  brain is more
 exquisite,  perfect,  and  complex,  its  functions
 ought to  be proportionally  so.   It is no slight
 proof of the doctrine now enforced,  that the fact
 is actually  thus:  that the  mental  powers  of
 brutes, so far as  we can see, are proportional  to
 their  organization.
  " We cannot deny to  animals all participation
 in  rational  endowments, without shutting our
 eyes  to the most obvious facts  ; to indications  of
 reasoning which the unprejudiced observation of
 mankind has not failed to recognise and appre-
 ciate. Without adverting to the well known in-
 stances of comparison, judgment, and sagacity in
 the elephant, the dog,  and  many  other animals,
 let us read the character drawn by Humboldt of

  • This is wt II illustrated in the plate at the beginning of Mr.
 While of Manchester's Essay on the Gradations of Man.  His
 plate is taktn from  Camper  and Blumenbach. Lawrence's
 ulates also are tVoin the same sources. 
41
the South American mules :  ' When the mules
feel themselves in  danger,  they  stop,  turning
their heads to the  right and  to the left.  The
motion of their ears seems to indicate that they
reflect on the  decision they ought to take. Their
resolution is slow, but always just, if it  be free;
that is to say, if it be not crossed or hastened by
the  imprudence of the traveller.   It  is  on the
frightful roads of the Andes, during journies of
six or seven months, across  mountains furrowed
by torrents, that the intelligence of horses  and
beasts of burthen displays itself in an astonishing
manner.  Thus the mountaineers  are  heard to
say, I will not give you the mule  whose step is
the easiest, but him who reasons  best.'  5 Pers.
Narr. 111.   If the intellectual phenomena of
man require an immaterial principle superadded
to the brain, we must equally concede it to those
more rational animals which exhibit manifesta-
tions differing from some of the human only in
degree.  If we grant it to these, we cannot re-
fuse it to the  next in order, and so on in succes-
sion to the whole  series; to the oyster, the sea
anemone, the  polype, the mycroscopic animal-
cules.  Is  any one prepared to admit the exis-
tence of immaterial principles in all these cases ?
If not, he must equally reject it in man.
   " It is admitted that an ideot with a mal-formed
brain, has no mind : that the sagacious  dog, and
half  reasonable  elephant do  not  require  any
thing to be superadded to their brains:  it is ad-
mitted that a dog or elephant excels inferior ani-
mals, in consequence of possessing a more per-
fect cerebral  structure; it is strongly suspected
that a Newton and  a Shakspeare excelled other
mortals  only  by  a  more  ample development of
the  anterior cerebral lobes ;  by having an  extra
inch of brain in the  right place ;* yet the Imma-

  * I do not think, with Mr. Lawrence, that the mere  size of
the brain is alone sufficient to account for difference of intellect:
                      D 2 
42
terialists will  not concede the obvious corollary
of all. these admissions, viz. that the mind of man
is merely that more perfect exhibition of mental
phenomena which the more  complete develop-
ment of the brain would lead us  to expect; but
they still perplex us with the gratuitous difficul-
ty of their immaterial hypothesis.  Thought (it is
positively and dogmatically asserted) cannot be
an act of matter.  Yet no feeling,  no thought, no
intellectual operation,  has  ever-been seen but in
conjunction with a brain; and living matter is
acknowledged by most persons to be capable of
what makes  the nearest  possible approach to
thinking.  The strongest advocate for Immate-
rialism seeks no  further than the body for his ex-
planation of all the vital processes of muscular
contraction, nutrition,  secretion,  &c operations
quite as different from any affection of inorganic
substance, as reasoning or thought: he will even
allow the brain to be capable of sensation.
  " WTho knows  the capabilities of matter so per-
fectly, as to be able to  say, that it  can see, hear,
smell, taste, and  feel, but cannot possibly  reflect,
imagine, judge ?  Who has appreciated them so
exactly, as to be able  to decide that it can exe-
cute the mental functions of  a dog, an  elephant,
or an ourang-outang, but cannot  perform  those
of a Negro or  a  Hottentot ?  To say of a  thing
known  only by negative  properties, that  is, an
immaterial substaace,  which is neither evidenced
by  aiiy  direct testimony,  nor by any indirect
proof from its effects,   that it does exist and can
thuik, is  quite  consistent in those who  deny
thought to animal structures, where we see  it go-
ing on every day !

the greater or less irritability of the whole nervous system—the
apt*.ess of the nervous syst*-m to admit associations—the facility
with wh'ch ideas of former impressions are called up by associa-
tion—the greater  permanence and  more extensive associations
of particular classes of impressions and ideas, &c. fcc. are  pro-
bably powerful sources of difference. 
43
  "if the menial processes do not constitute the
function of the brain, what is its office ?   In ani-
mals which possess only a small part of the hu-
man cerebral structure, sensation exists, and in
many cases is more acute than in man:  what em-
ployment shall we find for all that man possesses
over and above this portion—for the large and
prodigiously developed human hemispheres ? Are
we  to believe that these serve only to round the
figure of the organ, or to fill the cranium ?
  " It is necessary for you to form clear opinions
on  this subject, as it has a direct and immediate
reference to an important branch  of pathology.
They who consider the mental operations as acts
of  an immaterial being, and thus disconnect the
sound state of the mind from organization, act
very consistently in disjoining insanity also from
corporeal structure,  and in representing it as a
disease not of the brain, but of the mind (or Soul.)
Thus we come to a disease of an immaterial being!
for which, suitably enough, moral treatment has
been recommended.
  " I firmly believe, on the contrary, that the va-
rious forms of insanity—all the affections com-
prehended under  the general term, mental de-
rangement—are no other than evidences of cere-
bral affections.   They are disordered manifesta-
tions of those organs whose healthy action pro-
duces the phenomena called mental; they are, in
short,  symptoms  of  a diseased  brain.  These
symptoms have the same relation to the brain, as
vomiting, indigestion, heart burn, to the stomach;
cough, asthma, to  the lungs ;  or any other de-
ranged functions to their correspondent organs.
  " If  the biliary secretion be increased, dimi-
nished, suspended, or altered, we have no hesita-
tion in referring it to changes in the condition of
the liver as the immediate  cause of the pheno-
mena.  We explain the state of respiration, whe-
ther slow, hurried, impeded  by cough, spasm, 
41
&c.  by the  various conditions of the lungs and
other parts concerned in breathing.  These ex-
planations are deemed perfectly satisfactory.
  " What should we think of a person who told
us that  the organs had nothing to do  with the
business: that cholera, jaundice, hepatitis, are dis-
eases of an  immaterial hepatic being; that asth-
ma, cough, consumption, are affections of a  sub-
tle pulmonary matter; or that, in each  case, the
disorder is not in the bodily organs, but in a vi-
tal  principle?   If such a statement should be
deemed too absurd for  any serious comment in
the derangements of the  liver, lungs, and other
organic  parts, how can it  be received in  the
brain ?
  " The very persons who  use this language of
diseases of the mind, speak and reason correctly
respecting  the  other affections  of  the  brain.
When it is compressed by a piece of bone, or by
effused blood or  serum, and when all intellectual
phenomena are more or less completely suspend-
ed, they do not say that the mind is squeezed—
that the immaterial principle suffers pressure.
For the ravings  of delirium and frenzy, the exci-
tation and subsequent stupor of intoxication,  they
find  an  adequate explanation in the state of the
cerebral circulation, without  fancying  that the
mind is delirious, mad, or drunk. In these cases,
the seat of  the disease,  the cause of the  symp-
toms, is too  obvious to escape notice.  In many
forms of insanity, the affection of the cerebral
organization is  less  strongly  marked, slower in
its  progress,  but generally very  recognisable,
and  abundantly sufficient to explain the diseased
manifestations;—to  afford a  material  organic
cause for the  phenomena—for  the augmented or
diminished energy, or the  altered  nature of the
various  feelings  and intellectual faculties.
  " I have  examined, after death, the  heads  of
many insane  persons, and have  hardly seen  a 
45
single brain which did not exhibit obvious marks
of disease.  In  recent cases, loaded vessels, in-
creased serous secretions: in all instances of longer
duration, unequivocal signs of present or past in-
creased  action ; blood  vessels apparently more
numerous, membranes thickened  and  opaque;
depositions of coagulable lymph forming  adhe-
sions  or adventitious membranes ;  watery  effu-
sions; even abscesses.  Add to this, that the in-
sane  often become  paralytic, or are cut off'  by
apoplexy.
   " Sometimes,  indeed,  the  mental phenomena
are disturbed  without any visible deviation from
the healthy structure of the brain  ; as digestion
or biliary secretion  may  be  impaired or  altered,
without any recognisable change of structure in
the stomach or liver.   The brain, like other parts
of  this  complicated machine, may be  diseased
sympathetically ;* and we see it recover.  Thus
we find  the  brain,  like  other parts, subject to
what is  called functional disorder;  but although
we c*annot absolutely demonstrate  the fact, we
no  more  doubt  that the  material  cause  of the
symptoms or external signs  of disease  is in this
organ, than we do that impaired biliary secretion
has its source in the liver, or faulty digestion in
the stomach.   The brain  does not often come un-
der the inspection of the  anatomist  in such cases

  * As in puerperal cases. To this  reasoning of La-.vrence, I
would a<ld, (hat diseased brain may depend on the connexion be-
tween  the stomach, and bowels.  Thus, we set- diseased diges-
tion and morbid action of ihe intestines produce hypochondria
and melancholy ; such is often the case from worms.  Drunken-
ness affects the brain by means of the stomach, and prussic acid
kills by destroying th'- functions of the nt r\ous system.  The as
yet uutraced connexion of all the  parts of that system, by means
of which, when one part is disordered, a  distant part becomes
disordered also, i9.physiologically termed sympathy.  Thereby
intending that the connexion is as yet only  known by its effects,
»nd not anatomical!*  shewn.
  Dr. llasl.-im's publications on insanity corroborate strongly alt
Lawrence's reasoning. 
46
of functional disorder ; but I am convinced from
my own experience, that very few heads of per-
sons  dying  deranged  will be  examined  after
death,  without  shewing  diseased structure,  or
.evident signs of increased vascular activity. The
effect of medical treatment completely corrobo-
rates these views.  Indeed they who talk of, and
believe in, diseases of the mind,  are too wise to
put their trust in mental remedies.   Arguments,
syllogisms, discourses,  sermons, have never yet
restored any patient; the moral pharmacopeia is
quite inefficient; and no real benefit can be con-
ferred without vigorous medical treatment, which
is as efficacious in these affections as in the dis-
eases of other organs.*
  " In thus drawing your attention to the physi-
ology  of the brain,  I  have been influenced not
merely by the intrinsic interest and importance
of the subject, but by a wish to  exemplify the aid
which human and comparative anatomy and phy-
siology are capable of affording each other ; and
to shew how  the data furnished by both, tend  to
illustrate pathology.   I have purposely avoided
noticing those considerations of the  tendency of
certain physiological doctrines  which have  some-
times been industriously mixed  up with these dis-
quisitions.   In defence of  a weak cause, and in
failure of direct arguments, appeals to the pas-
sions  and prejudices  have been  indulged ; at-
tempts have  been  made to fix public odium  on
the maintainers of this or that  opinion; and di-
rect charges of bad motives and injurious conse-
quences, have been  reinforced  by all the  arts ot
 misrepresentation, insinuation,  and innuendo.
   " To discover truth, and to represent it in the

   • Mom! medicine can only act by introducing and  exciting
 new trains of ideas and of thought: but these are affections ot
 the brain in fact; and are therefore medicines operating directly
 on that organ.  All ideas, of whatever kind are motions excited
 in the brain, and there felt or perceived, 
47
clearest and most intelligible manner, seem 10
me the only proper objects  of  physiological, or
indeed any other inquiries. Free discussion is
the surest way not only to disclose and strength-
en  what is true, but to detect and expose what
is fallacious.  Let us not then pay so bad a com-
pliment to truth,  as  to use in its  defence  foul
blows and unlawful weapons.  Its adversaries, if
it have any, Avill  be  despatched soon enough,
without the aid of the  stiletto or  the bowl.   The
argument against the expediency of divulging an
opinion, although it be true, from the possibility
of its being perverted,  has been  so much hack-
neyed, so  often  employed  in the last resort by
the defenders of all established abuses, that  eve-
ry one who is conversant with the controversy,
rejects it immediately, as the sure mark of a bad
cause—as the last refuge of retreating error."
   So far  Mr. Lawrence.  Lectures on Physiolo-
gy, Zoology, and  the  Natural  History of Man.
8vo. London, 1819. Pages 105—115.   I have al-
ready assigned my reasons  for making this  ex-
tract so long.
  The following extract from Mr. Sawrey's edi-
tion of Dr. Marshall's Morbid Anatomy  of the
Brain, London, 1815, p. 209, will express my no-
tion of the functions of the brain and nerves  very
well, except that he has omitted the sympathetic
action on the  nervous   system of excited or de-
pressed states of the parts destined to internal
organic life, when different from their usual  and
natural states.  A morbid excitement or derange-
ment of any viscus will affect  the state of the
nerves belonging  to it, and by  sympathy  with
them, the general nervous  system.  Hence,  the
state of the brain, and the ideas  that arise in it,
will be more or less  modified by  the state of the
organic and internal apparatus destined to keep
up life.  Hence dreams from indigestion.  Hence
hypochondria from morbid action of stomach and 
48
 bowels.  Hence, the associations will, to a cer-
 tain degree, be modified by, and  depend  on the
 internal state of the body, as well as on external
 impressions ; and the sensations arising from ex-
 ternal impression will, to a certain degree, vary
 with the general state of health or disease. Hence
 sensations,  ideas,  and associations  may arise
 from the state of the internal organs, and are not
 exclusively dependant on  external impression.
  The following extract from  Dr. Andrew Mar-
 shall  will shew the generally received doctrine
 relating to  the functions and properties of the
 nerves, the  brain, and the nervous system ; and
 shew that my views of the subject are the same
 with that of all  well informed physiologists of
the present day :—
  Observations on the functions of the Brain and
Nerves, p. 209.  " The primary functions of the
brain and nerves  consist  in their rendering us
 conscious of the existence and properties of sur-
rounding objects : and while in this world, of the
existence and properties  of ourselves.  For al-
 though things exist  with all their properties inde-
 pendent of us, and therefore when a man perishes,
 not the smallest particle of surrounding  nature
 is annihilated,  or in  the  least unhinged by his
 dissolution, yet it is by our possessing brain and
 nerves, that the independent existence and pro-
 perties of surrounding objects come home to our
 perceptions.   Matter of the same form with that
 of the human body (except the brain and nerves)
 might exist and be  animated,  but without these
 organs, it would be  unconscious of its present ex-
 istence, or of  the properties and  various condi-
 tions of surrounding nature.
  " Living systems destitute  of  brain shew no
 signs of their being  impressed  with any feelingor
 consciousness. The polypus, according to the ob-
 servations of Haller and others, has no  brain or
 nerves: accordingly it appears  to perform  the 
49
motions requisite to its preservation by a neces-
sity of which it seems  to be unconscious.  Vege-
tables also are living systems, but having no brain
they  appear destitute of sense.  They take in,
assimilate, and apply  nourishment,  perform se-
cretions,  generate  and separate heat, preserve
their own substance from  putrefaction, perform
motions in consequence of irritations, and  pro-
duce prolific seed.  But all  these actions seem to
be performed from blind necessity, and without
any sort of intelligent consciousness.
  " But in living systems furnished with a brain
and nerves, so long as  they are entire, and in the
condition which  health gives  and requires, the
animal remains sensible of  the existence  of sur-
rounding nature, or susceptible of that conscious-
ness ;  but when injury is done to the brain,  the
Consciousness of the impressions resulting from the
r.ontact of external matter (of which kind are both
light and air) is, according to the degree of inju-
ry, perverted, suspended, or extinguished.   Yet
injuries inflicted  on other organs of the body, in
no wise affect the sense, unless when they symp-
tomatically involve the brain.  The same com-
parison, leading to  the same conclusion,  may be
made in respect to the diseases of the brain  and
other parts.
  " It must be admitted, that in order to produce -
peculiar sensations, there  must be the health and
entire structure of  the nerves in connexion with
the brain.  For  to destroy the extremities of
nerves, destroys the  peculiar  sensations which
these nerves exhibit while  remaining sound.  If
the retina be injured or destroyed, vision is im-
paired or lost; if the ultimate distribution of the
olfactory nerves be destroyed, there  is no more
smell.
  " Although light should be properly refracted,
yet if it should fall on the optic nerve before it
expands  into retina, it would  not occasion  any
                       E 
50
vision ; nor would odours, if conveyed to the ol
factory nerves within the scull, probably, give oc-
casion to smell; nor is it probable that sapid sub-
stances would excite a sense of taste, if applied
to any point of the nerves of taste other than the
nervous papillse of the tongue.
  " But necessary as the extremities of the nerves
are to the production of peculiar sensations, they
cannot be reckoned sentient: for if their connex-
ion  with the brain  be interrupted by compres-
sion,  no peculiar *sensation arises from impres-
sion on the extremities; but  if the compression
be removed, the power of giving the peculiar sen-
sation returns   Yet though  the compression  of
the nerves interrupts or  destroys the peculiar
sensations usually referred to. their extremities,
a sense of feeling in different modes, subsists be-
tween  the part  compressed and  the brain :  so
that the power of contributing to a certain degree
of sense, which would be lost  between the liga-
ture and the extremities,  survives between the
seat of the injury and the brain.  The sort  of
feeling so remaining is sometimes a sense of ob-
scure touch, sometimes a sense  of pricking or  a
sense of pain.
  " We therefore conclude that there is no man-
ner of sensibility in nerves but  in connexion
with the brain.   That the  power by which we
see, hear, feel, &c. is a  power  of the brain, the
nerves being only a conditio sine qua non  of par-
ticular sensations referred to  nervous  extremi-
ties, and the  brain being rather the efficient cause
of these sensations, and giving  susceptibility to a
certain degree  at least to that portion of nerve
left connected with it:—may it be. added, that in-
dependent of any conditional  impression on the
nerves, the brain  itself, from impressions imme-
diately on itself, is sentient; for let any set of
nerves whatever  be destroyed,  or let no particu-
lar impression whatever be made on  the  nerves, 
51
a sense of head ache, vertigo, noise, colours, &c.
may be, and often is produced by disease.*
  " The sphere of cerebral power exerted in con-
junction with, or in consequence  of impressions
made on the nerves, is great.   By the brain being
affected through the  medium of the eyes,  we are
made  acquainted with the colour, figure,  magni-
tude, and motion of  external things placed at a
greater  or less distance from us.  This is the
sense  of seeing:  an  inlet to  human  knowledge,
at once necessary to preservation, and to  open a
view of the striking  and beautiful phenomena of
nature.
  " The existence, degree of distance, hardness,
and  several other interesting qualities of objects
placed at a distance, seen or unseen, come  home
to our perceptions, through tremors of the air af-
fecting the "brain through  the ear.   This  is  the
sense  of hearing; by which we  are warned of
unseen  danger,  perceive  operations of  nature
though unseen,  and comprehend  the  signs or
words employed by our  fellow creatures to  ex-
press  their sensations and passions.
  " The qualities of sapid substances, which  we
are interested in perceiving, their sweetness, aci-
dity, bitterness,  saltness, and aromatic  nature,
are perceived, when these qualities , through  the
medium of the tongue, excite the proper sensa-
tions in the  brain.  This  is  the  sense of  taste.
The qualities  suggested by taste, constitute a
sort of index of the  salutary, innocent, or perni-

  • The experiments of Sir Everard Home  and M. Flearens
shew this. Moreover, as I have observed before in this tract,
the organic functions, which in a healthy state  go on without
producing sensation, in a diseased state, or in a state of great ex-
citement, do produce sensation, by affecting generally the whole
nervous apparatus.  In a state of over healthy excitement, (if 1
may so  express myself) dreams are sometimes more intensely
vivid  than their analogous waking  sensations.  So,  deranged
stomach and  bowels, and  worms, may produce hypochondria
idiocy,  and cveu mania. 
52
cious nature of substances presented as food, ra-
ther than point out the actual composition  of
these substances. This sense seems given chiefly
with a view to the  preservation of the animal;
for by it, man is  induced to take in wholesome
food,  and to  avoid  improper and  hurtful food :
the former being in general agreeable, and  the
latter, disagreeable, at least to  a  taste not cor-
rupted by luxury.   It is a common, yet curious
observation, that the same nerves which are sus-
ceptible  of impressions from  sapid substances,
are also  nerves of touch ; so that a substance  in
the mouth, is  both tasted and felt; its superficial
qualities of hardness, smoothness, &c. being also
perceived. This conjunction of both senses, seems
requisite in the tongue, since a  substance taken
into the mouth, may be as hurtful from its super-
ficial  qualities,  as  its roughness, angles, edges,
&c. is from its acrid,  saline, or putrid  qualities.
  " The  nourishment  and  refreshment of the
body, are farther assisted by our being enabled
to perceive certain  qualities of sapid substances
before we take them into  the mouth.  This is
done by  volatile particles of the substances af-
fecting the internal parts of the nose, and through
these the brain.   Thus, the  sense of smelling is
auxiliary to taste, as it admonishes us of the qua-
lity of sapid substances, before we  use them  too
freely ; as it induces us to take in proper food,
which is generally of a pleasant smell, if it smells
at all; and  as  it keeps us from unwholesome
food,  which is generally of a disagreeable odour.
Odours are the object of this sense; and different
odours affecting the brain through the nose, pro-
duce different sensations of smell, as either pun-
gent,  sweet,  or putrid, &c.  These suggest in
some degree,  what may be  expected from swal-
lowing or applying the substance ; but express
nothing concerning its internal structure or com-
position.  Air is the vehicle of odour. 
53
  " To assist vision, and to make amends for its
defects, there is a consciousness  implanted in us
of the contact of  external things.*   The nerves
that receive the impression from which this con-
sciousness results, are almost universally present
in the  body :  and if they remain  every where
free and connected, in a healthy state,  with an
entire and healthy brain, the contact of external
things, and internal changes,  are perceivable in
almost every part of the  body.  Several modes
of feeling may be marked: 1st. by the contact of
external things with the extremities of the nerves
of feeling, we acquire  a perception of the hard-
ness, softness, roughness, smoothness, heat, cold,
figure, magnitude, pressure, and  weight of what-
ever is within our reach.  This  is the  sense of
touch, properly so called ; the most  correct and
extensive of all the  senses,  subservient to self
preservation, and  supplying man with exact and
enlarged conceptions of what takes place in na-
ture.
   " 2dly. Certain  parts of the body occasionally
fall into a state  which gives rise to  a particular
mode of feeling, followed by certain propensities.
These give occasion  to actions, which being ex-
erted  relieve the propensity.  Thus a  certain
languid state of the circulation through the lungs,
gives  a peculiar uneasy sensation that  produces
yawning.  A sense of irritation in the nose gives
rise to sneezing ; a sense of  irritation about the

  • That is, we feel them when the) approach us near enough
to give rise to this sensation   There is no consciousness diffe-
rent from feeling or perception.  When the retina is excited by
the light of a candle, and tfe- motion is propagated along the op-
tic nerve to its extremity within the brain, I feel, I  perceive,  I
am conscious, of the impression We cannot be conscious of
the actual contact of bodies, because no psrticl s of matter are
in absolute contact.   They  recede without solution of continuity
by he;it, they contract by cob).  A ray of  li«hl impingwgjin  a
looking glass, is reflected, as Sir ls-iac Newton has shewn, at the
157th part of an inch previous to coi tact.  All this is well illus-
trated by the diagram of Father Uoscovich.
                        E 2 
54
glottis to coughing; a sense of tickling  of the
skin to laughter, &c.   Some of these peculiar
modes of sensation have names, and some have
not.  Like other sensations, they admit of no de-
finition.   Their final intention is evident, since
they tend to throw  off the offending cause that
produces them.
  " 3dly. Certain parts of the body are constant-
ly in a healthy state,  peculiarly susceptible of
impression ; such as the glans penis, and some
other parts; the final cause whereof, is also evi-
dent.
  " 4thly. All the parts of the body, supplied with
nerves, are susceptible  of impression which gives
occasion to sense of pain.  The impression here
arises  from  whatever hurts,  destroys, or forms
disease; and the sense  excited by  it, makes us
take pains to avoid injury, and get rid of disease,
By the bye, taking man as he is, and admitting the
laws of nature at present established, to be wise
and good, pain  is not an  evil, but the result of a
wise and  beneficent providence; since it tends
to preserve  our existence more unerringly and
directly than any other mode of sense with which
we  are endowed.  The exciting cause of pain is
the  impression of injury or disease : the efficient
cause,  the connexion of the part  so injured or
disordered with the  brain;  and the final cause,
the  preservation of the animal.  These are some
of the modes of feeling: each of the other  senses
is also  a genus, under which are included various
modes  of the sensation referred to the organ.
  " When we compare  the different senses toge-
ther, two or three observations occur to us; one
is, that the first f»ur senses, take place only when
certain due degrees of impression  are made on
the extremities of 'he nerves distributed to that
organ.   If the  impression  be too  slight,  no pe-
culiar  sense arises;  if  it exceed in  measure, in-
stead of the sense of seeing, hearing,  &c. there 
55
is merely a sense of pain.  Thus, the first four
senses, when their organs are injured, agree with
the sense of  feeling.   Another observation  is,
that as the sense of feeling arises from  impres-
sions made in those parts of the body,  so it is
more difficult to destroy  than the other senses.
When the extremities of  the nerves of the other
senses are destroyed,  peculiar sensations con-j
nected with them, also cease: but the remaining
body of nerves retains a sense of feeling: and the
extremities of the  nerves appropriated  to feel-
ing only, being destroyed, the extremities of the
portion left, resume the peculiar susceptibility of
the original extremities: thus, in the case of W.
Scott, whose penis  was carried off by a gun-shot,
the stump of it, which was even with the skin of
the pubis, resumed the peculiar sensibility  of the
glans penis : also the cicatrix of sores in  other
parts of the body, becomes susceptible to impres-
sions of touch.
   " But extensive as the  sphere of sensation is,
and how much soever of the universe, it unfolds
to human comprehension, the powers of the brain
are  not confined to  mere sensation.  The brain
is likewise the corporeal organ, whose health and
entire structure, are necessarily connected with
all intellectual  powers, all internal senses, and
all the passions.
   " Memory depends on the brain.  After living
but  a few weeks in the  world, exposed  to the
contact  of surrounding things, and to light  re-
flected from their surfaces, we  cannot  avoid re-
cognising sensations, as being mere repetitions of
similar impressions from  the same forms of mat-
ter.  We recognise the similar sensations, and
feel within ourselves,  that formerly we  were af-
fected exactly in a similar manner by the im-
pression on the organ of sense.   This  recognis-
ing of sensations and belief of their being repe-
titions, happens by  the same physical  necessity 
56
with  which the first sensations of  the kind we
ever had, avose from  the  original and first  im-
pressions.   We  cannot but  taste, when  sapid
substances are applied to the  tongue ; nor  can
we pass by the consciousness, that there is a re-
petition  when the same taste is  renewed.  This
is  the simplest form of memory : it  occurs in an
infant a month old, when  it begins  to recognise
its nurse.  After living longer, continually af-
fected with the true  sense  and impressions of
external things, and after being  masters of more
certain experience, we  naturally improve upon the
simpl. memory of a single  sensation, and acquire
gradually a power of  recalling a train of sensa-
tions, in the order and circumstances in which they
were  originally perceived.  They  are recalled
with a belief that they were formerly impressed
upon  us, by objects which  do not now affect us.
This is  memory in greater perfection.  A faculty
which, spiritual as it may seem, is seldom exert-
ed, but when it sets off from the vantage ground
of some  resembling, contrary,  or otherwise  re-
lated  actual sensation  of a present object.*
   "Judgment is  another power naturally found-
ed in  sensation.  For  to compare two sensations
together, to glide insensibly  into  a belief that
they are compatible or incompatible in the same
subject, are as necessary consequences of having
formed  the sensation,  as the sensations were the
consequences of the brains having  been affected
by the  impression.  Thus, if you present a  red
rose to  a child who never has seen one before,
but who has seen a v/hite rose, it has immediate-

  • Hume, in his Essay on  the -Connexion and  Association of
Ideas, and Lord Karnes in his Elements of Criticism, (Chapter
on Ideas occurring in a train) h«ve seen the same facts and rea-
soned in the same way.  But Dr. Hartley has treated tht* sub-,"
ject so plainly and yet so profoundly, that he Ims, in my opinion,
exhausted it: the objections of modern sciolists to that great mar.
notwithstanding. 
57
ly the complete sensation of a red rose : and it
it can speak it will express a judgment and  be-
lief that it is a red rose.  This is the birth of judg-
ment.
  " The power of reasoning in like manner grows
out of sensation.  For,  let a youth  after some
experience of the properties  of things, be sup-
posed master  of  two distinct independent per-
ceptions, but not to have experience enough to
incline him to a belief, that they are naturally
and  properly compatible  in  the same  object,
what resource has he?   If the determination in-
terests him,  he naturally  and immediately  re-
collects a  known third  perception, with which
one of the two sensations is known from experi-
ence to agree : and with this third recollected
perception, he is insensibly drawn to compare
the other perception.
  " Let it be inquired, will the eating of  the
berries of the  deadly nightshade kill me ?  I  run
back to some conception allied to the question;
as that these berries poisoned one of my neigh-
bours.  1 know that  I am of the same nature with
that neighbour; so  that as the berries poisoned
him, and I am of the  same  nature with him, I
conclude (as  a matter of experience,)  that they
will kill me.
  " In the same manner, might we  trace fancy ;
the power of abstraction ; and the power of clas-
sing things,  to their origin  from actual  sensa-
tion ;*  but that is at present declined.  I would
only remark,  that  all intellectual powers what-
ever, depend as much on the brain for their exer-
tion, as simple sensation does: for living systems
furnished with no brain, discover as little reason,
&c. as  they do sense : and injuries done  to  the
brain, of the nature of those enumerated  above,
while they hurt or suspend sense, hurt, suspend,
• Destut Tracey has done this. 
58
or pervert the powers of memory, reason, judg-
ment, &c.   Nay, in some  injuries and  diseases
of the brain, the powers of intellect are more de-
ranged  than those of pure sensation.   Maniacs,
in whom it has been proved,  that the brain is to-
pically  affected, and probably always in fault,
are often exact in particular sensations,  but err
widely  in judgment  and reasoning.  A sufferer
too under the operation of the trepan, is found
sometimes possessing feeling, but erring in rea-
son ; and  refers  the whole  operation, and all
that is  said and done, to some other  person.t

  "All  the internal senses also depend on the
brain, and  on  the perceptions which we cannot
help receiving, as we live under the continual
contact and impression of external things. These
are naturally stems, from which  the various ad-
ditional senses  called internal, branch  off.  We
cannot  hear sounds  agreeable in  combination,
without a sense of harmony.  We cannot see the
form of regularity  of parts,  and  the colour of
most flowers, without believing them to be beau-
tiful : nor understand the signs by which our fel-
low creatures express  or  betray  their  feelings,
without a belief, that they in return comprehend
our signs: nor  witness  their actions without ap-
proving some of them, and blaming others.  This
is the physical birth of the senses called internal,
which seem to be peculiar to man: and they also
depend on the brain.  For not to dwell  on other
instances, if the most delicate and chaste female
be seized with  a  phrenitis, she loses her habitual
sense of delicacy : and if injury or disease, in the
brain induces mania, the  maniac  ceases to  feel
the obligations  of morality.

  t l bnvi- omiMed here a disquisition of about a page and a half
on the nature of our .-.ense of bemty ; which did  not appear to
me necessary to the chain of reasoning. 
59
  " The distinction of sense  into  external and
internal, does not go to discriminate the two sets
of sense ; for they are equally internal and  ex-
ternal.   Nothing further can be understood than
that the one set of internal senses is excited
when external things affect the  organs  of sense :
but the other does not  immediately require  the
impression of external things  to produce them.
  " Lastly, all the passions and appetites depend
on the brain, for their corporeal organ.  Objects
whose properties come home to us through  the
primary sensations, do not leave us in  a state of
indifference.  The primary perceptions give birth
to senses called internal; and the internal senses
to appetites,  passions and volitions.  These  de-
pend upon the brain : not only because they grow
out of sense,  which  depends"  on that  organ, but
because when the brain is injured or diseased, it
is found equally or more severely  to alter, per-
vert, or extinguish passions and appetites.
  "In phrenitis, no  alteration is more remarka-
ble than alteration  and disorder m the passions.
This will appear from an unusual apprehension
of imaginary evils,  an  unusual anxiety about
friends, and  unusual hatred against enemies.  I
once saw a phrenetic patient with Dr. Pitcairn.
some of his senses were  lost ; taste in particular.
But  his regard for his wife was expressed in  a
tempest of passion ; it was  the  rage of love: at
other times he had the most delicate, yet ground-
less  jealousy.  Maniacs in  the  exacerbation of
their complaints, are preternafurallv irascible or
furious  ; they  go into fits of devotion with a  fer-
vour and religious awe, of which sound reason is
hardly susceptible.
  " There is a remarkable peculiarity in the state
pf the  brain,  observed as a law of the  animal
economy, which  is, that the  exertion is subjected
to a  periodical suspension more or less complete,
called sleep.   It is a complete suspension of the 
60
 power of the five senses, and of the action of the
 voluntary muscles ; for in sound sleep, particular
 sensations do not occur, nor are the powers which
 grow out of sensations  exerted.   But, in unquiet
 nights, though no actual sensation occurs,  no im-
 mediate  impression on any  organ of a  peculiar
 sense  being perceived,  the  powers  of memory,
 fancy, reason, and judgment, with various  inter-
 nal senses  and passions, are differently  exerted.
 They  proceed in an unusual way, not for want
 of reason, but from  want of  actual sensations to
 correct wrong judgments, and to direct all these
 powers according to the reality of things.*

  * The brain, as the chief seat of the nervous apparatus, is lia-
 ble to be affected by impressions made by external  objects on
 the senses—by any preternatural or morbid state of the organ
 itself—by any sympathetic affection with the internal organs or
 viscera—and by  the stale in which it  is put by the various asso-
 ciations of past  impressions.   Hence  when morbidly  excited,
 as in the lower states of phrenilis, apoplexy, or gout, sensations
 arise, both sleeping and waking, that would not occur in  its com-
 mon stale ; the impressions and associations are altered and mo-
 dified, and  all  intellectual processes are correspondentlv de-
ranged.  Why ?  Because according to the acknowledged axioms
of the schools, the character of the  recipient determines  the
mode of reception of the thing received ; quicquid recipitur, re-
cipitur ad modum recipientis.  Hence Mr. Owen of Lanark is
right in supposing that man is the creature of the circumstances
in which he is placed. Suppose four human beings with organs
similarly constituted  in all respects  at ten  years of age, one
bred up among the Brachmins of Hindostan, one as a Mussul-
man at Constantinople, one among the straite9t sect of Calvinis-
tic Secedei s, and one among the Savans of Paris: it is manifest,
the impressions  and  associations to which the nervous systems
of these beings would be respectively exposed from  the age ot'
ten to ihe agt of fifty would be extremely different: their intel-
lectual powtrs would be different, and the effect of motives and
of evidence  upon them, would be  as various as their various
educations.  For I submit the following reasoning as  unanswer-
able.  The  brain  (place  the  seat of sensation wherever you
please) is subject to the laws of the animal economy : it is pas-
sive in receiving impressions: the stale of the brain is modified
by the impressions it  receives: the state of its  associations of
imprefMuns with ideas, of ideas with ideas, depends upon the
actual state  of  the brain however produced : all the intellectual
powers consist of, and depend on, the associations of ideas (that
is, of associated  motions excited or occurring in the scat of sen-
sation :) hence all  intellectual powers and processes, whether 
61
  " The effect of sleep  is to restore the power of
the brain and nerves..  Independent of the seal-
ing up of actual sensation, the muscular parts in
themselves  require  periodical  suspension   or
abatement of their energy.   Long continued ac-
tual sensations, strong sensations lasting but for
a short  time, suffering of  moderate pain  for a
long  time,  or intense pain for  a  short  time,
much thinking,  pursuing  a long  tram  of abs-
tract reasoning, great  exertions of memory, &c.
gradually blunt the   powers  of  the  brain and
nerves, and a  cessation  of actual sensation oc-
curs: and, if in this insensible state,  other pow-
ers of the brain be exerted, their exertion is less
fatiguing than when we  are awake, because in
sleep, their  exertion is not  fixed or regulated  by
attention, which  is  one  of the  most  fatiguing
powers of the brain.   In  like manner,  long con-
tinued muscular action of the  voluntary muscles,
induces a sort of inability  in them,  and in sleep
their energy is restored.  On  awakening after a
due length of time spent  in sleep, all the powers
of the brain, and the energy of the muscles are
restored in  a proper degree.
   " I cannot quit this  part of the subject without

in potentia or in acta, are dependant on the state of the brain or
seal of sensation ; and therefore on the circumstances which
have produced this involuntary state of the ort>an, whatever
those circumstances may have been.  But let us t.-ike for grant-
ed a Soul.  Then if the brain can thus modify the Soul, and the
Soul thus modify the brain, are not both the one and the other
material—subject.to the  laws of organic matter?  What then
do you gain by introducing this creature of metaphysical fancy
—this hypothesis which addsnoforce and removes no difficulty?
Which must act upon matter,  and be acted on by matter, to
make its existence evident ?  Which those who believe in it ac-
knowledge to be a mere ens  rationis ?  Which has never been
seeu,vfelt, heard, or understood ?  Which is not cognizable by
any human inlet of knowtedge?  Whose introduction and pre-
tensions can be well traced to the power it affords the clergy
over the conduct and belief of their fellow creatures?  And
which can derive no countenance from  the words or actions of
Christ or his  Apostles,  or  the  general belief of the Christian
world for at least four centuries after Christ ?
                        F 
62
 observing that all the powers  proved to  belong
 to the brain, are equally peculiar in their nature.
 To be  conscious  of the figure of a circle, or the
 colour  of a flower, is as refined and  as  wonder-
 ful a power as reasoning is.   And  though these
 powers to the vulgar belief are  a necessary con-
 sequence of  an  impression on the organ of sense,
 they  have as little resemblance to such impres-
 sions, as reasoning in an abstract manner  has.*
   " There are yet two other questions,  which seem
 necessary to be considered.  First, whether the
 brain   properly so  called, and the   cerebellum,
 medulla spinalis,  &c.  possess equal sentient pow-
 ers ?t   No doubt  can remain that they do, when
 we consider  that  injuries or disease in whichever
 of these  integrant portions  of the whole mass
they happen, equally  occasion  stupor and  insen-
 sibility, or are  accompanied with violent exer-
tions of the muscular  powers.   But the muscu-
lar disorder is most obvious, when those parts are
 affected which give origin to  nerves, that supply
 the involuntary muscles.   Also, injuries or dis-
 ease prove equally fatal,  whether in  the  brain,

  * This passage seems to allude favourably to Berkely's hypo-
 thesis. In fact, the external world is an hypothesis to account for
 our sensations; but an hypothesis to which we are  irresistibly
 driven by the laws of the animal economy, which compel us to
 resort to it.  Doubtless, as our author says, there is as much diffi-
 culty involved in the fact of sensationor perception, as in  any pro-
 cess (if reasoning.  They are both processes depending on the
 properties of the bodily organ employed in them : properties,
 which we can no more explain than we can explain.the  cause of
 life, or electricity, or gravitation.  These are" all  properties be-
 longing to the substance with which we find them connected. In
 like manner, perception or sensation, thought, volition, &c. are
 properties of the substances with which  we find  them connect-
 ed.  If the latter require a Soul to explain them, so do the for-
 mer ; no good reason exists in one case, that does not in the
 other.  If gravitation be an essential property of any given mass
 of matter, so is perception and thought of the nervous appara-
tus of the human being; and for like reason in both cases, viz.
 we see them constantly accompanying each other.
  f Further experiments are necessary to  determine this.
 Those of Sir Everard Home and M. Fleurens, if followed up,
 would assuredly  throw light on the funetions peculiar to the va-
 rious parts of this organ. 
63
 cerebellum,  medulla oblongata,  or medulla spi-
 nalis.  A man is killed by being shot through the
 head.  The  fiercest bull  is instantly killed by
 thrusting a knife through  between the first ver-
 tebra, and the posterior edge of the foramen mag-
 num occipitis into the beginning of the medulla
 spinalis.*   An elephant  is killed in the same
 manner.   Robert Walker, a soldier,  was killed
 by a shot through the cauda equina.   Lastly, the
 equal sentient power of these different  portions
 is evinced, by their giving  origin to nerves of par-
 ticular organs of sense.   The brain gives nerves
 to the nose and eyes ; the  cerebellum to the skin,
 muscles of the face, the tongue  and  the  teeth.
 The medulla oblongata gives nerves to  the ear;
 the medulla  spinalis  to  the  muscles and skin
 of most of the body.
   " The second question is, whether  the whole
 substance of the brain, cerebellum, &c. be equally
 sentient?. The nerves proceed from the medul-
 lary,  not the cineritious part.  This  continuity
 of substance, compared with the effects  of tying,
 dividing, or destroying nerves,  renders it pro-
 bable, that it is principally  the  medullary parts
 of the brain, which are the origin of the power as-
 cribed to it.t  The medullary substance of all the
 portions forms one continuous mass, is apparent-
 ly  fibrous, the fibres  being incredibly minute,!

  * This experiment of Vesalius,  Dr. W. Hunter used toexhi-
 bit to his class on a jackass.  It is the Spanish mode of killing,
 not only at their bull fights, iiut among their butchers; and it is
 doubtless a humane one.
  t There are some facts of lesions of the brain, that have not
 yet been explained. Many are collected on dubious authority
 by Dr. Ferriai- in his letter to Th. Cooper, Esq.  in  the fourth
 volume of the Manchest*r Transactions; and many on better au-
 thority by  Sir Everard  Home.  Anatomists and physiologists,
 however, agree in considering these anomalies as not militating
 against the genera! .position.  Futare experiments may well ex-
 plain them. . We are in the infancy of medullary physiology as
yet.
  ± Gall & Spurzheiin's anatomical exhibitions of the struc-
 ture of th-e'brain, I apprehend, have settled  tbefibi-ous nature of
medullary  substance, in the way nearly as Marshall has stated it.
The other  parts of their Craniology are not so clear.
ZW *»• ~VX*- : 
64
convolved in regular intricacy, apparently with-
out beginning, and ending  no where but in the
extremities of nerves.   The two hemispheres of
the brain communicate by transverse medullary
bands, and by  the union of their crura;  while
the medullary crura of cerebellum, blend  with
the medullary crura of cerebrum, &c.
  "In the next place, in Haller's experiments on
living animals, instituted to  determine the diffe-
rent degree of sensibility of different parts of the
body, it appeared that  the victim of his inquiry,
manifested most evident signs of pain, and fell
into most violent convulsions, when  the  medul-
lary substance of the brain was pierced or broken
down : but that these symptoms were less consi-
derable when the injury  was confined to the ci-
neritious substance.*   Accidental injuries  seem
also to hurt or disorder sense, according as  they
extend their effects to  the medullary  substance.
A blow on the upper part of the head, does not
stun so suddenly, as a blow  near the base of the
scull; the cineritious substance abounding in the
upper part; the medullary  being exterior in the
basis  of the encephalum.
  " If judgment may be formed from one or two
cases, a fracture with depression of the os frontis,
causes less stupor than a fracture with depres-
sion of  the parietal bones—the anterior lobes of
the brain being supported  on the  orbitar  pro-
cesses of the frontal bones: but the middle part
of the hemispheres gravitating on the whole me-
dullary substance below, the  compression must
extend its influence to the whole.  These opi-
nions are strengthened by the case of a soldier,
who recovered after being shot through the fore
part of the cranium ; and from another in whom
a piece of the barrel of a gun, was beaten into the

  •  I  refer to Sir Everard Home's experiments, before alluded
to. 
65
fissura magna sylvii, where it remained two days
without any violent  symptom, being lodged chief-
ly in the cineritious substance.
  " From  these  circumstances,  it is concluded,
that the medullary substance at the origin of the
nerves, is  principally  concerned  in the functions
ascribed to the  brain;  and if  it would  throw
greater light on the subject to determine the seat
of the  soul, we would allege that the whole me-
dullary substance is that seat.*
   " So much  we have advanced  respecting the
precise function  of the  brain.   It is established
we  hope, beyond all doubt, that  the  brain so far
as  a corporeal  organ  is  concerned,  gives sensa-
tion,  intellect,  volition,  appetite, and  passion.
Beyond these,  its powers  seem not to extend as
we  shall endeavour to shew   By the  brain, man
is  rendered  speculative and  capable of under-
standing,  ttlld  ot the  oamc time im.lilied  t«l aC-
tion: and  is thus fitted  for the place he holds in
the system of nature.t

  •  He says well, if it would throw greater light on the subject.
What light can be thrown on the functions of the b: 'in, t\v the
supposition of its connexion with a being  totally an<i essentially
dissimilar in its nature, and having no common property with
the matter of which the brain is composed?  But if the seat of
the Soul be in the medullary substance, then has the Soul all 'he
properties of matter, and is material.  For having relation to,
and occupying space, and space too of a determinate form, then
has  the Soul solidity, extension, and figure: and as the Soul is
placed there  to act upon the brain, she has the common proper-
ties of all matter, attraction and repulsion, into which all action
upon matter (by  common consent) can be  resolved.
  t  Here ends the physiology of this sensible writer; to all
of which (subject to the  limitations which I have expressed in
these notes)  I subscribe, as an excellent  compendium  of that
branch of Metaphysics called Ideology ; and beyond all  compa-
rison conveying that real knowledge which Dr. Dugald Stewart,
-with his metaphysical predecessors of the same  school at his
heels, was so grossly deficient in.   More is to  be learnt from
this  summary of Dr. Marshall of genuine physiological  meta-
physics, than from all the pages of inanity of the writers so much
in vogue among those who read without thinking. A man who
.will separate metaphysics from physiology, is not to be reasoned
with. 
66
   " It is unnecessary we presume, to  guard the
account given, by subjoining that when  we call
the brain  the  sole organ of  sensation, and of all
the  powers superadded  to  sensation,  we  only
mean  the sole corporeal organ.  For reason and
the testimony of God  declare, that in man there
is an immaterial substance, which has a share in
perception, thinking, and reasoning, &c—-a mind
united with the brain.   But an inquiry into the
human Soul, is not within the design of  this pa-
per.  In  this  account of the brain, no mention is
made of the Soul,  because it  is only the corpo-
real organ of  the powers explained,  that we are
considering.   That  there is a Soul within us, as
well as an omnipotent spirit that fills,  sustains,
and actuates the universe, I firmly believe.   No
less  do I  believe so from reason,  than from the
sacred monuments of divine inspiration.   But it
is to be observed, that in this state  of our  exis-
tence, no  act of the mind, can be, or ever is ex-
erted, without a corresponding condition  of  pow-
er in the brain.  Brain and Soul, though it is un-
known to  us, how they are united, are joint agents
in this world.   The power and health of the for-
mer, in every exercise of sense, judgment, me-
mory, passion,  &c. is  indispensably necessary,
and equally so with the presence of  the mind.
Besides, the brain, and not the Soul, is the pro-
per object of medical or surgical treatment.  Had
we introduced the mind into our discussion, we
must have thrown the brain  into the back ground;
or have encumbered the narration,  with a con-
stant coupling of brain and mind.5'—p. 244.
   Thus far, Dr.  Marshall,  on the  functions of

   I consider all  that follows of Dr. Marshall from the end of
this paragraph, as a sacrifice on the altar of prudence to popular
prejudice.  Lawrence is cried down for refusing to pay this-ho-
mage to the priesthood ; and most disgraceful it is to Abernethy
to have encouraged this hue and cry of ignorance and bigotry
against a fellow professor. 
67
the brain  and nerves.   It  is manifest, that he,
like Dr. Rush,  and  many  others, was a mate-
rialist ; but was  restrained  by popular prejudice,
from bringing the whole truth into open day.   I
cannot blame  him.   Who  can  see the obloquy
connected with the character of  Mr. Lawrence,
notwithstanding his  eminent learning,  industry,
and professional skill  and  knowledge, without
excusing  the  writers,  who  shelter  themselves
from  the  yellings of the bigots,  set on by those
whose interest it is to cry  out, " Great is Diana
of the Ephesians.'' ? If the present clerical  com-
binations in which all sects join, however discor-
dant on  other  subjects, should succeed to bring
on again  the night of  ignorance, (which  1 much
fear will be  the case,) the advocates of truth,
must rest contented  with having deserved the
 success they could not obtain.
FINIS.