What has preceded suffices to prove, that the interior organ of man, which is called his soul, is purely material. He will be enabled to convince himself of this truth, by the manner in which he acquires his ideas,—from those impressions which material objects successively make on his organs, which are themselves acknowledged to be material. It has been seen, that the faculties which are called intellectual, are to be ascribed to that of feeling; the different qualities of those faculties which are called moral, have been explained after the necessary laws of a very simple mechanism: it now remains, to reply to those who still obstinately persist in making the soul a substance distinguished from the body, or who insist on giving it an essence totally distinct. They seem to found their distinction upon this, that this interior organ has the faculty of drawing its ideas from within itself; they will have it, that man, at his birth, brings with him ideas into the world, which, according to this wonderful notion, they have called innate. The Jews have a similar doctrine which they borrowed from the Chaldeans: their rabbins taught, that each soul, before it was united to the seed that must form an infant in the womb of a woman, is confided to the care of an angel, which causes him to behold heaven, earth, and hell: this, they pretend, is done by the assistance of a lamp, which extinguishes itself as soon as the infant comes into the world. Some ancient philosophers have held, that the soul originally contains the principles of several notions or doctrines: the Stoics designated this by the term PROLEPSIS, anticipated opinions; the Greek mathematicians, KOINAS ENNOIAS, universal ideas. They have believed that the soul, by a special privilege, in a nature where every thing is connected, enjoyed the faculty of moving itself without receiving any impulse; of creating to itself ideas, of thinking on a subject, without being determined to such action, by any exterior object; which by moving its organs should furnish it with an image of the subject of its thoughts. In consequence of these gratuitous suppositions, of these extraordinary pretensions, which it is only requisite to expose, in order to confute some very able speculators, who were prepossessed by their superstitious prejudices; have ventured the length to assert, that without model, without prototype to act on the senses, the soul is competent to delineate to itself, the whole universe with all the beings it contains. DESCARTES and his disciples have assured us, that the body went absolutely for nothing, in the sensations, in the perceptions, in the ideas of the soul; that it can feel, that it can perceive, that it can understand, that it can taste, that it can touch, even when there should exist nothing that is corporeal or material exterior to ourselves. But what shall be said of a BERKELEY, who has endeavoured, who has laboured to prove to man, that every thing in this world is nothing more than a chimerical illusion; that the universe exists nowhere but in himself; that it has no identity but in his imagination; who has rendered the existence of all things problematical by the aid of sophisms, insolvable even to those who maintain the doctrine of the spirituality of the soul.
Extravagant as this doctrine of the BISHOP OF CLOYNE may appear, it cannot well be more so than that of MALEBRANCHE, the champion of innate ideas; who makes the divinity the common bond between the soul and the body: or than that of those metaphysicians, who maintain that the soul is a substance heterogeneous to the body; who by ascribing to this soul the thoughts of man, have in fact rendered the body superfluous. They have not perceived they were liable to one solid objection, which is, that if the ideas of man are innate, if he derives them from a superior being, independent of exterior causes, if he sees every thing in God; how comes it that so many false ideas are afloat, that so many errors prevail, with which the human mind is saturated? From whence comes these opinions, which according to the theologians are so displeasing to God? Might it not be a question to the Malebranchists, was it in the Divinity that SPINOZA beheld his system?
Nevertheless, to justify such monstrous opinions, they assert that ideas are only the objects of thought. But according to the last analysis, these ideas can only reach man from exterior objects, which in giving impulse to his senses modify his brain; or from the material beings contained within the interior of his machine, who make some parts of his body experience those sensations which he perceives, which furnish him with ideas, which he relates, faithfully or otherwise, to the cause that moves him. Each idea is an effect, but however difficult it may be to recur to the cause, can we possibly suppose it is not ascribable to a cause? If we can only form ideas of material substances, how can we suppose the cause of our ideas can possibly be immaterial? To pretend that man without the aid of exterior objects, without the intervention of his senses, is competent to form ideas of the universe, is to assert, that a blind man is in a capacity to form a true idea of a picture, that represents some fact of which he has never heard any one speak.
It is very easy to perceive the source of those errors, into which men, otherwise extremely profound and very enlightened have fallen, when they have been desirous to speak of the soul: to describe its operations. Obliged either by their own prejudices, or by the fear of combatting the opinions of some imperious theologian, they have become the advocates of the principle, that the soul was a pure spirit: an immaterial substance; of an essence directly different from that of the body; from every thing we behold: this granted, they have been incompetent to conceive how material objects could operate, in what manner gross and corporeal organs were enabled to act on a substance, that had no kind of analogy with them; how they were in a capacity to modify it by conveying its ideas; in the impossibility of explaining this phenomenon, at the same time perceiving that the soul had ideas, they concluded that it must draw them from itself, and not from those beings, which according to their own hypothesis, were incapable of acting on it, or rather, of which they could not conceive the manner of action; they therefore imagined that all the modifications, all the actions of this soul, sprung from its own peculiar energy, were imprinted on it from its first formation, by the Author of Nature: that these did not in any manner depend upon the beings of which we have a knowledge, or which act upon it, by the gross means of our senses.
There are, however, some phenomena, which, considered superficially, appear to support the opinion of these philosophers; to announce a faculty in the human soul of producing ideas within itself, without any exterior aid; these are dreams, in which the interior organ of man, deprived of objects that move it visibly, does not, however, cease to have ideas—to be set in activity—to be modified in a manner that is sufficiently sensible—to have an influence upon his body. But if a little reflection be called in, the solution to this difficulty will be found: it will be perceived that, even during sleep, his brain is supplied with a multitude of ideas, with which the eye or time before has stocked it; these ideas were communicated to it by exterior or corporeal objects, by which they have been modified: it will be found that these modifications renew themselves, not by any spontaneous, not by any voluntary motion on its part, but by a chain of involuntary movements which take place in his machine, which determine, which excite those that give play to the brain; these modifications renew themselves with more or less fidelity, with a greater or lesser degree of conformity to those which it has anteriorly experienced. Sometimes in dreaming, he has memory, then he retraces to himself the objects which have struck him faithfully;—at other times, these modifications renew themselves without order, and without connection, very differently from those, which real objects have before excited in his interior organ. If in a dream he believes he sees a friend, his brain renews in itself the modifications or the ideas which this friend had formerly excited—in the same order that they arranged themselves when his eyes really beheld him—this is nothing more than an effect of memory. If in his dream he fancies he sees a monster which has no model in nature, his brain is then modified in the same manner that it was by the particular, by the detached ideas, with which it then does nothing more than compose an ideal whole; by assembling, and associating, in a ridiculous manner, the scattered ideas that were consigned to its keeping; it is then, that in dreaming he has imagination.
Those dreams that are troublesome, extravagant, whimsical, or unconnected, are commonly the effect of some confusion in his machine; such as painful indigestion—an overheated blood—a prejudicial fermentation, &c.—these material causes excite in his body a disorderly motion, which precludes the brain from being modified in the same manner it was on the day before; in consequence of this irregular motion the brain is disturbed, it only represents to itself confused ideas that want connection. When in a dream, he believes he sees a Sphinx, a being supposed by the poets to have a head and face like a woman, a body like a dog, wings like a bird, and claws like a lion, who put forth riddles and killed those who could not expound them; either, he has seen the representation of one when he was awake, or else the disorderly motion of the brain is such that it causes it to combine ideas, to connect parts, from which there results a whole without model, of which the parts were not formed to be united. It is thus, that his brain combines the head of a woman, of which it already has the idea, with the body of a lioness, of which it also has the image. In this his head acts in the same manner, as when by any defect in the interior organ, his disordered imagination paints to him some objects, notwithstanding he is awake. He frequently dreams, without being asleep: his dreams never produce any thing so strange but that they have some resemblance, with the objects which have anteriorly acted on his senses; which have already communicated ideas to his brain. The watchful theologians have composed, at their leisure, in their waking hours, those phantoms, of which they avail themselves, to terrify or frighten man; they have done nothing more than assemble the scattered traits which they have found in the most terrible beings of their own species; by exaggerating the powers, by enlarging the rights claimed by tyrants, they have formed ideal beings, before whom man trembles, and is afraid.
Thus, it is seen, that dreams, far from proving that the soul acts by its own peculiar energy, that it draws its ideas from its own recesses; prove, on the contrary, that in sleep it is intirely passive, that it does not even renew its modifications, but according to the involuntary confusion, which physical causes produce in the body, of which every thing tends to shew the identity, the consubstantiality with the soul. What appears to have led those into a mistake, who maintained that the soul drew its ideas from itself, is this, they have contemplated these ideas, as if they were real beings, when, in point of fact, they are nothing more than the modifications produced in the brain of man, by objects to which this brain is a stranger; they are these objects, who are the true models, who are the real archetypes to which it is necessary to recur: here is the source of all their errors.
In the individual who dreams, the soul does not act more from itself, than it does in the man who is drunk, that is to say, who is modified by some spirituous liquor: or than it does in the sick man, when he is delirious, that is to say, when he is modified by those physical causes which disturb his machine, which obstruct it in the performance of its functions; or than it, does in him, whose brain is disordered: dreams, like these various states, announce nothing more than a physical confusion in the human machine, under the influence of which the brain ceases to act, after a precise and regular manner: this disorder may be traced to physical causes, such as the aliments—the humours—the combinations—the fermentations, which are but little analogous to the salutary state of man; from hence it will appear, that his brain is necessarily confused, whenever his body is agitated in an extraordinary manner.
Do not let him, therefore, believe that his soul acts by itself, or without a cause, in any one moment of his existence; it is, conjointly with the body, submitted to the impulse of beings, who act on him necessarily, according to their various properties. Wine taken in too great a quantity, necessarily disturbs his ideas, causes confusion in his corporeal functions, occasions disorder in his mental faculties.
If there really existed a being in Nature, with the capability of moving itself by its own peculiar energies, that is to say, able to produce motion, independent of all other causes, such a being would have the power of arresting itself, or of suspending the motion of the universe; which is nothing more than an immense chain of causes linked one to another, acting and re-acting by necessary immutable laws, and which cannot be changed, which are incapable of being suspended, unless the essences of every thing in it were changed, without the properties of every thing were annihilated. In the general system of the world, nothing more can be perceived than a long series of motion, received and communicated in succession, by beings capacitated to give impulse to each other: it is thus, that each body is moved by the collision of some other body. The invisible motion of some soul is to be attributed to causes concealed within himself; he believes that it is moved by itself, because he does not see the springs which put it in motion, or because he conceives those powers are incapable of producing the effects he so much admires: but, does he more clearly conceive, how a spark in exploding gunpowder, is capable of producing the terrible effects he witnesses? The source of his errors arise from this, that he regards his body as gross and inert, whilst this body is a sensible machine, which has necessarily an instantaneous conscience the moment it receives an impression; which is conscious of its own existence by the recollection of impressions successively experienced; memory by resuscitating an impression anteriorly received, by detaining it, or by causing an impression which it receives to remain, whilst it associates it with another, then with a third, gives all the mechanism of reasoning.