The functions of man are the most interesting objects of Science. Physics
and Morals are equally involved by them. It is in them that the physical
sciences terminate, and that the moral sciences have their origin.
Of what avail are the former, but to develope the influence of external
bodies upon the functions of man? What are the latter, but the results of
the reaction of that influence upon men in society?
To explain them is the business of physiology; and if it have hitherto
failed in doing so—if it have even neglected the noblest of all the
functions—I should say the noblest branch of philosophy—the intellectual
functions of man, and have abandoned them to persons totally incapable of
developing them, because totally ignorant of the structure on which they
depend, and who have left them in a state of greater obscurity than that
in which they found them, that is the fault of physiologists, and not of
their science.
In these lectures, I shall at least be influenced by the deepest sense of
such errors.
But it is not merely the philosophy of the human mind, or rather of
the intellectual functions of man, that have thus been abandoned to
barbarism. The science itself has never been systematized; and all its
individual parts have been so neglected, that the other sciences and the
arts dependent upon it, have been left in similar obscurity.
I shall endeavour to shew that it is by the aid of physiology alone that,
in explaining the functions of the eye, for instance, we can render
perfect the theories of colour and of vision; that, in explaining the
functions of the ear, we can construct rational ones of phonics and of
hearing; that in explaining the functions of the organ of voice, we
can illustrate the formation of letters, and the origin of languages;
that, in explaining the functions of the muscles, we can establish those
first principles of taste in the fine arts, the very existence of which
have so often been questioned, and so deliver a theory of movement and
of attitude, applicable to sculpture, the higher species of painting,
gesture in oratory, &c. In fine, it is by physiological means only,
that we can construct a natural theory of medicine, and render precise
and easy, the most delicate and the most difficult of the operations of
surgery.
To effect these purposes, nothing is more necessary than arrangement,
because it at once involves facts and their theory, or the reasonings
founded upon them.
* * * * *
In considering a natural arrangement of Anatomy and Physiology, it
appears to me an unquestionable point, that it ought to indicate, at a
single glance, the relation of all the functions to and their dependence
upon each other.
It is upon this principle that I have constructed the natural arrangement
which I am about to detail; and a single remark upon the arrangements
adopted by the most celebrated modern physiologists, will, at once, shew
the originality of the plan which I propose, and point out the errors of
arrangement which I deprecate.
Blumenbach, Chausier, Dumas and Bichat, treat of circulation before
absorption, on which it depends, and even before mastication, deglutition
and digestion, on which, in general, even absorption itself chiefly
depends.
If the arrangement of Chausier in particular, who, in this respect, is as
accurate as any of them, were to be considered as indicating the relation
and dependence of the functions, so absurd is it, that absorption instead
of the cause, would be the result of nutrition, generation the result of
absorption, and digestion the result of generation. Thus, by arranging
effects in the place of causes, they confound the relations of the
functions, and reverse the very order of their dependence.
The division of the functions into external and internal, as anciently
proposed by Aristotle, and afterwards successively adopted and improved
by Buffon, Grimaud and Bichat (the last of whom substituted for them the
terms organic and animal) is still more faulty.
Anatomy, I divide into three parts, namely that which considers the
mechanical or loco-motive organs, that which considers the vital organs,
and that which considers the intellectual organs.
Under the mechanical or loco-motive organs, I class, first, the bones
which support the rest of the animal structure; second, the ligaments
which unite them; and third, the muscles which move them.
Under the vital organs, I class, first, the organs of digestion, the
absorbent surfaces, and the vessels which absorb from these surfaces;
second, the heart, lungs and blood-vessels, which derive their contents
(the blood) from the absorbed lymph; and third, the organs of secretion,
which separate various matters from the blood. Then follow the generative
organs, which, though generally formed into a distinct class from the
vital, ought not by any means to be so reckoned. For it is evident, that
they form, as it were, the sequel of the vital organs, being dependent
on secretion—the last of the vital functions, and destined merely to
propagate vitality, and to communicate it to a new series of beings.
Under the intellectual organs, I class, first, the organs of sense, where
impressions take place; second, the brain or organ of judgment, where
these excite ideas; and third, the nerves, where volition results from
the last.
This is a natural arrangement of the anatomy of animals, and its peculiar
simplicity is illustrated by its involving, in application, that of
minerals and vegetables, and by its being capable of instant adaption to
physiological science.
In order to arrange Animal Physiology, it is only necessary to substitute
the term “functions” for “organs;” and that science will likewise
involve, in application, the physiology of mineral and vegetable bodies,
and be, in its turn, capable of instant adaption to medical science.
Thus, the functions also are divided into Mechanical, Vital and
Intellectual.
The mechanical functions are subdivided into that of support, that of
connection, and that of loco-motion.
The vital functions are divided into that of absorption, that of
circulation, and that of secretion.
The intellectual functions are divided into that of sensation, that of
mental operation, and that of volition.
A circle of functions, I may observe, thus exists in animals, which
exists not in minerals or vegetables, because volition, the last of
the intellectual functions, connects itself to the mechanical ones, by
rendering them subservient to it in loco-motion. Thus the first and
the last of these functions are as intimately connected as any of the
intermediate ones, and a beautiful circle of organic function and organic
influence is formed.
The plan of the course will, therefore, be precisely the same with that
which I have proposed for Anatomy and Physiology in general.
I. In that part of the course which relates to the mechanical organs and
functions, will be explained the structure and uses, _1st_, of the bones
which support the rest of the animal machine; _2dly_, of the ligaments
which unite it; and _3dly_, of the muscles which move it.
II. In the first part of the course which relates to the vital organs and
functions, will be explained the structure and uses, _1st_, of the organs
of mastication, deglutition and digestion, of the absorbent surfaces,
and of the vessels which absorb from these surfaces; _2dly_, of the
heart, lungs and blood-vessels, which derive their contents, (the blood),
from the absorbed lymph; and, _3dly_, of the organs of secretion, which
separate various matters from the blood. Throughout this division in
particular, the analogies from vegetables will be explained.
III. In that part of the course which relates to the intellectual organs
and functions, will be explained the structure and uses, _1st_, of the
organs of sense which receive impressions from external objects; _2dly_,
of the brain, where these impressions excite ideas; and, _3dly_, of the
spinal marrow and nerves, where volition results from the last. In this
division, will be also explained, as founded upon original observations,
certain criteria of the various degrees of the sensitive, perceptive and
voluntary powers possessed by different animals, as well as the nature of
sensation, perception and volition themselves.
As in physiological enquiries, comparative anatomy and comparative views
alone can destroy an hypothesis or transmute it into a theory, I shall
throughout the course introduce all its principal facts.
The machines, says Cuvier, which are the object of our researches, cannot
be demonstrated without being destroyed. We have no means of discovering
what would result from the absence of one or several of their parts, and
consequently we remain ignorant of the operation of each of these parts
in producing the total effect.
Fortunately, nature herself seems to have prepared for us the means of
supplying that want which arises from the impossibility of making certain
experiments on living bodies. The different classes of animals exhibit
almost all the possible combinations of organs. We find them united, two
and two, three and three, and in all proportions; while at the same time
it may be said that there is no organ of which some class or some genus
is not deprived. A careful examination of the effects which result from
these unions and privations is therefore sufficient to enable us to form
probable conclusions respecting the nature and the use of each organ, or
form of organ.
In the same manner, we may proceed to ascertain the use of the different
parts of the same organ, and to discover those which are essential, and
separate them from those which are only accessary. It is sufficient
to trace the organ through all the classes which possess it, and to
examine what parts constantly exist, and what change is produced in the
respective functions of that organ, by the absence of those parts which
are wanting in certain classes.
Thus, says Richerand, the cellular structure of the lungs which cannot be
clearly demonstrated in man, on account of the excessive tenuity of their
smallest lobuli, evidently displays itself in the vesicular lungs of
salamanders and frogs; in the same manner, the scales covering the bodies
of fish and reptiles, or the claws of birds, give us a just idea of the
structure of the epidermis, and of the disposition of its small laminæ
that are laid over each other on a part of their surface, &c.
Vegetable life, justly, says the same author, compared in its resources
and effects with animal life, would throw very great light on several
phenomena, which, at present, it is difficult for us to conceive and to
explain.
The medical treatment of vegetables, which is almost entirely surgical,
would be equally benefited by these researches.
Thus the wounds of vegetables, like those of the human body, are much
less dangerous when their surface is smooth, than when their edges
are rough, lacerated, or contused. Trees cut down with a saw bud with
difficulty, whilst those felled with an axe vegetate more briskly.—The
saw tears the vegetable structure and produces a greater or less
alteration in organization. The unequal surface of a tree thus cut down
retains humidity, as destructive to the trunk, of which it induces a
rottenness, as too great a quantity of pus, that so habitually moistens
the surface of an animal wound, destroys granulation and prevents
cicatrization.
In considering the application, or rather the relation of physiology to
philosophy in general, the philosophy of mind will be particularly dwelt
upon.
In considering the application of physiology to the fine arts, the error
in the construction of the antique statues, and of those of Michael
Angelo, both with regard to the individual muscles supposed to be brought
into action, and with regard to a hitherto unobserved principle of
attitude, will be carefully pointed out.
In considering the application of physiology to the medical and
surgical arts, a view of a new, simple and impressive natural system
of medical science in general, and of its first principles as an art,
will be exhibited; and rules will also be given for performing surgical
operations with the utmost precision and ease, upon the principle of
an invariable relation between the arrangement of internal, and the
situation of certain external parts, which consequently form accurate
signs of that arrangement.
* * * * *
I may now observe, that the series of beings which the arrangement I have
just delivered involves, all more or less evidence the phenomena of life
and intellect, as well as exhibit structure, and I may conclude with a
few observations concerning these phenomena.
Minerals have properly been said to exist, plants to exist and live,
animals to exist, live and think.
These are all modifications of each other, as I shall afterwards shew;
but, at present, I shall limit my observations to the two last of these
classes, and to the additional phenomena, namely those of life and
intellect, which they more strikingly exhibit.
I shall not, however, like some of the most celebrated modern
physiologists, occupy my preliminary lectures with long details
concerning their nature; but, as I reckon life to be the mere result of
organization, I shall, throughout the course, illustrate it in connexion
with those organs on which it depends, and shall, at present, only take a
general view of its nature.
Life is a term which some philosophers have hitherto inaccurately
employed as expressing an imaginary principle, though it merely
designates a series of dependent actions. This they were doubtless
induced to do by that artifice which has ever induced weak men to assume
an air of knowledge by giving a particular name to what they did not
understand; and the same artifice still induces such persons to blame
those who endeavour to explain the phenomena of life according to obvious
physical laws, precisely because a successful explanation would at once
exhibit their ignorance and their desire to conceal it.
Life has, with equal absurdity, been termed a forced state, though it
merely evinces a series of phenomena in justest unison with those of the
universe. I dissent, therefore, from those who assert, that we employ the
terms _life_ and _vital force_ to express what are apparent exceptions to
general laws. This is only a repetition of the error of Brown. It was,
however, an erroneous conclusion from accurate observations.
For example, says Cuvier, let us contemplate a female in the prime of
youth and health,—that elegant voluptuous form—that graceful flexibility
of motion—that gentle warmth—those cheeks crimsoned with the roses of
delight—those brilliant eyes, darting rays of love, or sparkling with the
fire of genius—that countenance enlivened by sallies of wit, or animated
by the glow of passion, seem all united to form a most fascinating being.
A moment is sufficient to destroy this illusion. Motion and sense often
cease without any apparent cause; the body loses its heat; the muscles
become flat; and the angular prominences of the bones appear; the lustre
of the eye is gone; the cheeks and lips are livid.... These, however,
are but preludes of change still more horrible. The flesh becomes
successively blue, green and black. It attracts humidity; and while one
portion evaporates in infectious emanations, another dissolves into a
putrid sanies, which is also speedily dissipated. In a word, after a
few short days, there remains only a small number of earthy and saline
principles. The other elements are dispersed in air and in water to enter
again into new combinations.
This, Cuvier adduces as a proof that the possession of life prevents the
operation of external physical causes. The picture is perfectly correct,
but the conclusion unauthorised.
It was indeed impossible for us not to feel the frequent necessity of
deploring those we loved. We therefore thought that we perceived this
principle operating when the evident influence of external causes, or
some mysterious agency seemed to drive the noblest results of life,
intellect and genius, from the philosopher and statesman, who had, by
the diffusion of truth and resistance to arbitrary power, preserved
the liberties, and aggrandized the happiness of nations; we thought we
perceived their influence when imagination’s powers fled from the poet
whose song had once almost conferred new life on the heroes of ancient
times; we thought we perceived their influence when the phenomena of
vital action disappeared in the body of the patriot hero in whom they
had once developed the noblest specimen of that generous love of social
life which induced him to devote his existence to his country’s weal; we
thought we perceived their influence when those magic charms abandoned
the lovely female whose powers had once excited from the philosopher
those splendid epithets that ranked her with the other objects of his
adoration, celestial truth and god-like genius—which had obtained even
from the poet those wonderful strains that at once immortalized him and
the object of his song—which had commanded, even in the hero, those
glorious devotions which, for far too short a period, illustrated the
ever memorable days of chivalry. When those eyes whose soft languor had
fascinated every beholder, those cheeks where life had often spread the
crimson veil of love—when these were gone, those eyes were dim and sunk,
those cheeks were pale, those lips were livid, that bosom depressed,
that form rigid and icy cold, when all had thus assumed the darkest
and most frightful hues, had gradually lost cohesion and become one
mass of horrible putrescence, whose infectious effluvia now threatened
destruction almost welcome to those who once adored the animated being—it
was scarcely possible to feel all this, and avoid the conclusion that
life was a state of force.
It was doubtless this unknown and imaginary power connecting the various
phenomena of organic structure that gave origin to the idea of life. But
that they are no state of force is proved by this, that while the only
notion we have of them is motion—successive attraction and repulsion,
electricity, fire &c. exhibit precisely corresponding phenomena, and the
last of these was, I believe, on that single account, considered as the
symbol of life and intellect by the great Zoroaster.
This and similar facts, I may remark, convince me, that the earth has
myriads of times been illumed by the highest attainments of intellect,
and as often plunged into darkness. This single point of Indian
philosophy was, in my opinion, but the mere shadow of the highest
excellence in philosophy in general; and as the greatest cultivation of
the human mind, and the greatest misapplication of its faculties, cannot
well exist together, I am equally convinced, that the beautiful specimens
of art, blended with heterogeneous absurdities, in the monuments of
Upper Egypt, afford the most striking proof that, contrary to the common
assertion, there _were_ periods in that country when tyrants held no
despotic sway over the physical, nor the priests of a false religion over
the moral structure of man.
But to return to the subject.—True it is that the affinities of external
agents with the molecules of organic bodies are precisely the same during
life when their influence is resisted as after death when it operates
with the greatest energy; but the power which during life organic bodies
possess of resisting the influence of external agents, and even the
extension of the sphere of their action beyond the mere bounds of the
living body, is, in my opinion, very easily accounted for.
All the particles of matter possess attraction and repulsion, and the
largest homogeneous masses, _coeteris paribus_, evidence them most.
Hence, organic bodies, while they possess homogeneity by the subsistence
of intimate relations between their parts, evidence attraction and
repulsion in the highest degree. While in infancy, these relations are
merely forming, the powers of attraction and repulsion are weak; when,
in the vigour of life, these relations are most intimate, these powers
are greatest; when, in old age, these relations are interrupted, these
powers are also diminished; and when, in death, these relations cease
to exist between the molecules, or in other words, when the body is no
longer organized, the power of combined resistance terminates.
Thus, life is no forced state, but an intrinsic power arising merely from
the intimate relation of these molecules, and the greater effects which,
in such combinations, they are capable of producing, than when, in death,
they have become independent of each other, and their powers disunited,
are capable of much less effectual resistance.
Thus, it is, that I would endeavour to shew a connexion between the
phenomena of living bodies, and the general laws of nature.
This general and common motion of all the parts, says even Cuvier, forms
so peculiarly the essence of life, that the parts which are separated
from a living body soon die, because they possess no motion of their own,
and only participate in the general motion produced by their union. Thus,
according to the beautiful expression of Kant, the mode of existence of
each part of inanimate bodies belongs to itself; but, in living bodies,
it resides in the whole.
When, I say, that life consists in motion, I make no assertion derogatory
to the Deity, for every philosopher is of opinion that motion is to us
as mysterious as life; and when I endeavour to trace in its phenomena
a correspondence with physical laws, I conceive that I pay the truest
homage to a Deity. At all events, it would be dishonest of me to give my
sanction to opinions respecting a difference which seems to me not to
subsist.
The same causes which terminate motion terminate life. Life begins
by motion, and terminates when it ceases; but very curiously it also
terminates in consequence of it. In other words, the motion wears out
the machine in which it takes place. For, while the functions are most
dependent, life encreases; and their very independence, though, to a
certain extent, the grand aim of existence, destroys it. The very cause
of decay commencing when the different functions have acquired their
greatest vigour, arises precisely from their having acquired that vigour,
and being, at that moment, most capable of a species of warfare, if I
may so term it, with each other, as well, as in some measure, from the
greater number of accidents to which a complexity of functions is liable.
That, at this period, the functions may, in a certain sense, be said
to combat each other, will be evident to every one who, for a moment,
considers that great exercise of the loco-motive functions uniformly
interrupts the vital and intellectual, or of the vital functions injures
the loco-motive and intellectual, or of the intellectual functions
injures the loco-motive and vital.
These powers are always in an inverse relation to each other.
Grimaud seems to have had some idea of this, with regard to the first
and second classes of functions. He, says Richerand, has given the most
extensive developement to the idea of the constant opposition between
those two series of actions, over which preside, according to the opinion
of this physician, two powers, which he calls loco-motive and digestive.
It is marked in no species of animals more than in the carnivorous,
which connect with senses abounding in stratagem, and muscles capable of
extraordinary action, an assimilating power of so low a degree, that
their aliment, in order to be conveniently digested, must posses a
composition analogous to that of their organs.
Thus, the independence which the functions acquire, and the interruptions
which their operations present to each other, subjects them to the common
laws of impeded motion, and its result, a separation of parts.
When, in manhood, their unison is most complete, life is most vigorous.
When, in old age, this unison ceases, life disappears. Hence also, I
am convinced, it is, that those animals whose functions are longest
dependent on each other, and who remain longest helpless, longest enjoy
organic existence.
As motion only can result from motion, so life can only result from
life. The vital actions of all animals originate in those of their
parents, from whom they are detached precisely when their actions
become sufficiently independent of them. I am convinced it is upon this
principle, that the egg is detached from the ovary and the fœtus from
the uterus, as well as because, in these cases, the ovary and the uterus
themselves, after long quiescence, recover an independent action of their
own. The same power which enables an organic body to act by itself,
forces it to separate from another.
Life then seems, in a great measure, to consist in the successive
attraction and repulsion of particles—properties equally common to
minerals, vegetables and animals, though in different manners and
degrees. Life, however, is not here to be confounded with sensibility,
which nevertheless I shall afterwards shew is also possessed by all of
them. Life seems inseparable from generation, nutrition and decay, or,
in other words, from origin, increase, diminution—a progression which
minerals and vegetables pass through as well as animals. Minerals also
increase by additions to their external surfaces, vegetables by absorbing
from without inward, and animals by absorbing from their internal as well
as external surfaces.
* * * * *
By the intellectual functions, I understand the actions of the
intellectual organs, or, in other words, those actions which constitute
mind. With soul—the sacred and revered province of theologians, I do
not wish in the slightest degree to interfere; not for the harsh reason
assigned by atheists, namely, that the whole empire of ignorance, the
direction of the basest passions, and the gun or bayonet of the soldier
are under their command (these are sentiments which I never shall
profess), but for a juster and a better reason, namely this, that soul
is, in truth, their proper province.
Sensation, then, seems to be entirely dependent on touch, which, in the
other senses, is only modified so that one receives one kind of it, and
another receives another; thus the tongue is touched by means of liquids,
the nose by means of odours, the ear by aeriform vibrations, and the eye
by light.
All the other intellectual functions are nevertheless mere modifications
of sensation. Upon them, therefore, we shall not dwell, but, by taking
into view some important facts in anatomy, which have a relation to all
of them, I shall be able to explain sensation in particular.
Sommering has observed, that man has the largest brain in proportion to
the nerves given off from it; and that this proportional magnitude, may,
in every instance, be referred to as the best criterion of the degrees of
intelligence. Now, it appears to me not at all difficult to account for
this fact (the general truth of which may be granted), by comparing it
with another not less important, viz. that, in the inferior classes of
animals, the nervous system becomes, as you descend, more and more widely
diffused.
Hence, I deduce this important principle, viz. that the degrees of
intellect are, in all animals, in exact proportion to the concentration
of the nervous system.
Now, the more equally distributed this system is, the more independent
of each other are the parts of organized beings, or, in other words, the
necessity of a connection of these parts increases, in proportion to
the magnitude of the common trunk compared with the rami. It is only,
therefore, in the more perfect animals, that the connection of the
different parts of the nervous system, and particularly the presence of
central parts, is necessary to the existence of the different functions.
Animals, on the contrary, having this sensitive substance very generally
diffused, when mutilated, recover their figure, or, when cut into pieces,
form several individuals, having each a system of sensation and volition.
The larger warm-blooded animals acquire pieces of flesh analogous to
those which have been cut away; crabs acquire new claws; the tadpoles of
frogs and water newts acquire new limbs and tails; and the lower end of
the snail, having been divided from the upper, acquires a new head. The
earth and boatworm, when divided into considerable pieces, form several
new individuals; but animals having this system still more generally
diffused, as the polypus, when divided into the smallest fragments, each
fragment self-exists and becomes a perfect individual.
This also is more or less the case with plants. As you descend among
them, their parts become less dependent on each other. The dicotyledons,
which possess irritability, sleep and the principle of life most
diffused, and which, among plants, are analogous to the dicordated
animals, namely quadrupeds and birds, possess concentric fibres and
the most diffused sensibility; the monocotyledons, analogous to the
monocordated animals, namely reptiles and fishes, possess more numerous
centers and less diffused sensibility; and the acotyledons, analogous to
the acordated animals, possess most numerous centers and least diffused
sensibility.
As, in some worms and zoophytes, there is indeed no appearance of nerves,
and certainly none in plants, which yet possess sensibility, all this
gradually approaches to the attraction and repulsion of the magnet and
electrics, which, like some of these, are divisible almost to infinity,
and yet possess their various powers, which, like the sensibility of the
superior animals, connected by nerves, are only evidenced when led by
conductors.
Hence, I conclude, that sensation, understood in this limited sense,
as distinct from perception, and differing, _toto coelo_, from soul,
is, like extension, an imprescriptible property of all matter: but it
may exist in as many forms and as many relations as it; in its separate
particles; in larger combinations, as polypes; in still larger ones, as
worms and insects, where these extended and sentient particles, connected
by nerves, have more extensive relations and more complete dependence on
each other; or uniting to constitute perception in whole bodies, as in
the more perfect animals, where a sensorium commune exists, and where, in
consequence of the most exquisite arrangement, and the finest relations,
no particle can be deranged without affecting all the rest.
It is indeed, these various degrees in which it appears, that afford
a strictly analogical proof of its existence as a primary property of
matter.
As man then has not only sensation in the separate parts, but perception
arising from the whole, the descent is gradual to beings which have
merely sensation in distinct parts, but no general perception; and
thence equally gradual to beings which have sensation limited to their
individual particles.
Now, as the perceptions of two of the superior animals cannot unite to
form one perception, so the sensations of two parts of a polyp cannot
combine in perception; nor is it of course more wonderful, that the
sensations of two of the minute particles of matter cannot unite in one
common sensation.
As we do not expect electricity to be evidenced without conductors, why
should we expect sensation, in any great degree, without those nerves
which are its conductors? It would be as irrational to deny the former,
when conductors are not present, as to deny the latter (understood as I
have defined it), when nerves are absent.
Neither is it more wonderful that these sensations, thus limited, are not
evidenced; because it is scarcely to be expected, that the functions of
that should be evident, the absolute structure of which is unknown, and
because it is exactly in proportion to the concentration of sensation
(and by no means to its division) that it is, at any time, evidenced.
Upon the same principle, it is, that the particles of a pigment, when in
contact, are more evident than when extended over an immense surface,
or that a combination of pullies and one cord produce more evident
motion than each of them, with separate cords, could separately. But it
is unnecessary to accumulate illustrations—the principle pervades all
nature, and every natural operation illustrates it.
Nor do we merely find evident sensibility thus produced by the various
arrangements of matter: it is implicitly dependent on all the changes of
bodies, and is identified with their motions, by being suspended whenever
these are suspended. Of this, the hybernation of animals, the winter
state of most plants, the state of the embryo in utero or in ovo, of the
chrysalids of insects, the nymphs of worms, and the seeds of plants,
afford examples.
Nor is this all: but evident sensibility may be produced and destroyed at
pleasure by a mere alteration in the arrangement of the particles of one
and the same body; as in the wheel animal, and the anguillæ of tiles.
Nor is even this all: you may, if you choose, by the mere arrangement
of the particles of matter, as I shall afterwards prove by experiment,
at once produce myriads of animals, and bestow upon them motion, or in
other words, the phenomena of sensibility. This, the experiments of
Spallanzani, contrary to his own inclination, decidedly prove.
If it be objected, that it may be as fairly argued, that sensation is
something combined with these forms of matter, I answer, that we are not
entitled to suppose any thing an independent being which never appears
but in combination.
Now, as we have shown that sensation is implicitly dependent upon, or
connected with motion; and as this and all the other functions of the
brain, are entirely the results and modifications of sensation, they also
must be dependent on or connected with motion.
Far be it from me to pretend to account for mental operation by mere
physical motion. But, that motion accompanies all these processes, I am
certain; nor can the supposition that motion is made use of in the most
mysterious operations of the mind, possibly detract from the honour of a
Deity, or from our admiration of natural operations.
We have little need to be afraid of a moderate and rational materialism.
It is the idealism of Berkeley, it is the scepticism of Hume—those
dangerous opponents of such materialism, that have so deeply injured
philosophy and religion. It is according to these systems, that prophets,
apostles and miracles, are only ideas in the mind; and, indeed, the
unreasonable dislike to a rational materialism, is alone chargeable with
having led to the dangerous scepticism of Hume.
That physiologists, then, should so long have permitted others to
encroach upon their proper province, is disgraceful to them, and has
been most mischievous to science. To this is owing the barbarism of the
doctrine of mind. As physiologists abandoned it, philosophers found it
difficult to give it a name.—Some called it morals—others metaphysics—and
others, the philosophy of the mind. But I have just endeavoured to shew,
that it is neither morals nor metaphysics, nor the philosophy of the
mind—but the philosophy of the intellectual organs of the human body.
FIRST PRELIMINARY LECTURE TO THE COURSE OF PATHOLOGY AND THE PRACTICE
OF MEDICINE; EXHIBITING THE OUTLINE OF A NATURAL SYSTEM OF PATHOLOGY,
MEDICINE AND THE MATERIA MEDICA.