Chapter VII: Part I (4)

If all the preceding conjectures be refused by those opposed to us; if it be pretended that Nature acts by a certain quantum of immutable and general laws; if it be believed that men, quadrupeds, fish, insects, plants, are from all eternity, and will remain eternally, what they now are: if I say it be contended, that from all eternity the stars have shone, in the immense regions of space, have illuminated the firmament; if it be insisted, we must no more demand why man is such as he appears, then ask why Nature is such as we behold her, or why the world exists? We are no longer opposed to such arguments. Whatever may be the system adopted, it will perhaps reply equally well to the difficulties with which our opponents endeavour to embarrass the way: examined closely, it will be perceived they make nothing against those truths, which we have gathered from experience. It is not given to man to know every thing--it is not given him to know his origin--it is not given him to penetrate into the essence of things, nor to recur to first principles--but it is given him, to have reason, to have honesty, to ingenuously allow he is ignorant of that which he cannot know, and not to substitute unintelligible words, absurd suppositions, for his uncertainty. Thus, we say to those, who to solve difficulties far above their reach, pretend that the human species descended from a first man and a first woman, created diversely according to different creeds;--that we have some ideas of Nature, but that we have none of creation;--that the human mind is incapable of comprehending the period when all was nothing;--that to use words we cannot understand, is only in other terms to acknowledge our ignorance of the powers of Nature;--that we are unable to fathom the means by which she has been capacitated to produce the phenomena we behold.

Let us then conclude, that man has no just, no solid reason to believe himself a privileged being in Nature; because he is subject to the same vicissitudes, as all her other productions. His pretended prerogatives have their foundation in error, arising from mistaken opinions concerning his existence. Let him but elevate himself by his thoughts above the globe he inhabits, he will look upon his own species with the same eyes he does all other beings in Nature: He will then clearly perceive that in the same manner that each tree produces its fruit, by reason of its energies, in consequence of its species: so each man acts by reason of his particular energy; that he produces fruit, actions, works, equally necessary: he will feel that the illusion which he anticipates in favour of himself, arises from his being, at one and the same time, a spectator and a part of the universe. He will acknowledge, that the idea of excellence which he attaches to his being, has no other foundation than his own peculiar interest; than the predilection he has in favour of himself--that the doctrine he has broached with such seeming confidence, bottoms itself on a very suspicious foundation, namely IGNORANCE and SELF-LOVE.

CHAP. VII.

_The Soul and the Spiritual System_.

Man, after having gratuitously supposed himself composed of two distinct independent substances, that have no common properties, relatively with each other; has pretended, as we have seen, that that which actuated him interiorly, that motion which is invisible, that impulse which is placed within himself, is essentially different from those which act exteriorly. The first he designated, as we have already said, by the name of a SPIRIT or a SOUL. If however it be asked, what is a spirit? The moderns will reply, that the whole fruit of their metaphysical researches is limited to learning that this motive-power, which they state to be the spring of man's action, is a substance of an unknown nature; so simple, so indivisible, so deprived of extent, so invisible, so impossible to be discovered by the senses, that its parts cannot be separated, even by abstraction or thought. The question then arises, how can we conceive such a substance, which is only the negation of every thing of which we have a knowledge? How form to ourselves an idea of a substance, void of extent, yet acting on our senses; that is to say, on those organs which are material, which have extent? How can a being without extent be moveable; how put matter in action? How can a substance devoid of parts, correspond successively with different parts of space? But a very cogent question presents itself on this occasion: if this distinct substance that is said to form one of the component parts of man, be really what it is reported, and if it be not, it is not what it is described; if it be unknown, if it be not pervious to the senses; if it be invisible, by what means did the metaphysicians themselves become acquainted with it? How did they form ideas of a substance, that taking their own account of it, is not, under any of its circumstances, either directly or by analogy, cognizable to the mind of man? If they could positively achieve this, there would no longer be any mystery in Nature: it would be as easy to conceive the time when all was nothing, when all shall have passed away, to account for the production of every thing we behold, as to dig in a garden or read a lecture.--Doubt would vanish from the human species; there could no longer be any difference of opinion, since all must necessarily be of one mind on a subject so accessible to every enquirer.

But it will be replied, the materialist himself admits, the natural philosophers of all ages have admitted, elements and atoms, beings simple and indivisible, of which bodies are composed:--granted; they have no more: they have also admitted that many of these atoms, many of these elements, if not all, are unknown to them: nevertheless, these simple beings, these atoms of the materialist, are not the same thing with the spirit, or the soul of the metaphysician. When the natural philosopher talks of atoms--when he describes them as simple beings, he indicates nothing more than that they are homogeneous, pure, without mixture: but then he allows that they have extent, consequently parts, are separable by thought, although no other natural agent with which he is acquainted is capable of dividing them: that the simple beings of this genus are susceptible of motion--can impart action--receive impulse--are material--are placed in Nature--are indestructible;--that consequently, if he cannot know them from themselves, he can form some idea of them by analogy: thus he has done that intelligibly, which the metaphysician would do unintelligibly: the latter, with a view to render man immortal, finding difficulties to his wish, from seeing that the body decayed--that it has submitted to the great, the universal law--has, to solve the difficulty, to remove the impediment, given him a soul, distinct from the body, which he says is exempted from the action of the general law: to account for this, he has called it a spiritual being, whose properties are the negation of all known properties, consequently inconceivable: had he, however, had recourse to the atoms of the former--had he made this substance the last possible term of the division of matter--it would at least have been intelligible; it would also have been immortal, since, according to the reasonings of all men, whether metaphysicians, theologians, or natural philosophers, an atom is an indestructible element, that must exist to all eternity.

All men are agreed in this position, that motion is the successive change of the relations of one body with other bodies, or with the different parts of space. If that which is called _spirit_ be susceptible of communicating or receiving motion--if it acts--if it gives play to the organs of body--to produce these effects, it necessarily follows that this being changes successively its relation, its tendency, its correspondence, the position of its parts, either relatively to the different points of space, or to the different organs of the body which it puts in action: but to change its relation with space, with the organs to which it gives impulse, it follows of necessity that this spirit most have extent, solidity, consequently distinct parts: whenever a substance possesses these qualities, it is what we call MATTER, it can no longer be regarded as a simple pure being, in the sense attached to it by the moderns, or by theologians.

Thus it will be seen, that those who, to conquer insurmountable difficulties, have supposed in man an immaterial substance, distinguished from his body, have not thoroughly understood themselves; indeed they have done nothing more than imagined a negative quality, of which they cannot have any correct idea: matter alone is capable of acting on our senses; without this action nothing would be capable of making itself known to us. They have not seen that a being without extent is neither in a capacity to move itself, nor has the capability of communicating motion to the body; since such a being, having no parts, has not the faculty of changing its relation, or its distance, relatively to other bodies, nor of exciting motion in the human body, which is itself material. That which is called our soul moves itself with us; now motion is a property of matter--this soul gives impulse to the arm; the arm, moved by it, makes an impression, a blow, that follows the general law of motion: in this case, the force remaining the same, if the mass was two-fold, the blow should be double. This soul again evinces its materiality in the invincible obstacles it encounters on the part of the body. If the arm be moved by its impulse when nothing opposes it, yet this arm can no longer move, when it is charged with a weight beyond its strength. Here then is a mass of matter that annihilates the impulse given by a spiritual cause, which spiritual cause having no analogy with matter, ought not to find more difficulty in moving the whole world, than in moving a single atom, nor an atom, than the universe. From this, it is fair to conclude, such a substance is a chimera--a being of the imagination. That it required a being differently endowed, differently constituted, to set matter in motion--to create all the phenomena we behold: nevertheless, it is a being the metaphysicians have made the contriver, the Author of Nature. As man, in all his speculations, takes himself for the model, he no sooner imagined a spirit within himself, than giving it extent, he made it universal; then ascribed to it all those causes with which his ignorance prevents him from becoming acquainted, thus he identified himself with the Author of Nature--then availed himself of the supposition to explain the connection of the soul with the body: his self-complacency prevented his perceiving that he was only enlarging the circle of his errors, by pretending to understand that which it is more than possible he will never be permitted to know; his self-love prevented him from feeling, that whenever he punished another for not thinking as he did, that he committed the greatest injustice, unless he was satisfactorily able to prove that other wrong, and himself right: that if he himself was obliged to have recourse to hypothesis--to gratuitous suppositions, whereon to found his doctrine, that from the very fallibility of his nature, these might be erroneous: thus GALLILEO was persecuted, because the metaphysicians, the theologians of his day, chose to make others believe what it was evident they did not themselves understand.

As soon as I feel an impulse, or experience motion, I am under the necessity to acknowledge extent, solidity, density, impenetrability in the substance I see move, or from which I receive impulse: thus, when action is attributed to any cause whatever, I am obliged to consider it MATERIAL. I may be ignorant of its individual nature, of its mode of action, or of its generic properties; but I cannot deceive myself in general properties, which are common to all matter: this ignorance will only be increased, when I shall take that for granted of a being, of which from that moment I am precluded by what I admit from forming any idea, which moreover deprives it completely either of the faculty of moving itself, giving an impulse, or acting. Thus, according to the received idea of the term, a spiritual substance that moves itself, that gives motion to matter, and that acts, implies a contradiction, that necessarily infers a total impossibility.

The partizans of spirituality believe they answer the difficulties they have accumulated, by asserting that "_the soul is entire--is whole under each point of its extent_." If an absurd answer will solve difficulties, they certainly have done it. But let us examine this reply:--it will be found that this indivisible part which is called soul, however insensible or however minute, must yet remain something: then an infinity of unextended substances, or the same substance having no dimensions, repeated an infinity of times, would constitute a substance that has extent: this cannot be what they mean, because according to this principle, the human soul would then be as infinite as the Author of Nature; seeing that they have stated this to be a being without extent, who is an infinity of times whole in each part of the universe. But when there shall appear as much solidity in the answer as there is a want of it, it must be acknowledged that in whatever manner the spirit or the soul finds itself in its extent, when the body moves forward the soul does not remain behind; if so, it has a quality in common with the body, peculiar to matter; since it is conveyed from place to place jointly with the body. Thus, when even the soul should be admitted to be immaterial, what conclusion must be drawn? Entirely submitted to the motion of the body, without this body it would remain dead and inert. This soul would only be part of a two-fold machine, necessarily impelled forward by a concatenation, or connection with the whole. It would resemble a bird, which a child conducts at its pleasure, by the string with which it is bound.

Thus, it is for want of consulting experience, by not attending to reason, that man has darkened his ideas upon the concealed principle of his motion. If, disentangled from prejudice--if, destitute of gratuitous suppositions--if, throwing aside error, he would contemplate his soul, or the moving principle that acts within him, he would be convinced that it forms a part of its body, that it cannot be distinguished from it, but by abstraction; that it is only the body itself, considered relatively with some of its functions, or with those faculties of which its nature, or its peculiar organization, renders it susceptible:--he will perceive that this soul is obliged to undergo the same changes as the body; that it is born with it; that it expands itself with it; that like the body, it passes through a state of infancy, a period of weakness, a season of inexperience; that it enlarges itself, that it strengthens itself, in the same progression; that like the body, it arrives at an adult age or reaches maturity; that it is then, and not till then, it obtains the faculty of fulfilling certain functions; that it is in this stage, and in no other, that it enjoys reason; that it displays more or less wit, judgment, and manly activity; that like the body, it is subject to those vicissitudes which exterior causes obliges it to undergo by their influence; that, conjointly with the body, it suffers, enjoys, partakes of its pleasures, shares its pains, is sound when the body is healthy, and diseased when the body is oppressed with sickness; that like the body, it is continually modified by the different degrees of density in the atmosphere; by the variety of the seasons, and by the various properties of the aliments received into the stomach: in short, he would be obliged to acknowledge that at some periods it manifests visible signs of torpor, stupefaction, decrepitude, and death.

In despite of this analogy, or rather this continual identity, of the soul with the body, man has been desirous of distinguishing their essence; he has therefore made the soul an inconceivable being: but in order that he might form to himself some idea of it, he was, notwithstanding, obliged to have recourse to material beings, and to their manner of acting. The word _spirit_, therefore, presents to the mind no other ideas than those of breathing, of respiration, of wind. Thus, when it is said the _soul is a spirit_, it really means nothing more than that its mode of action is like that of breathing: which though invisible in itself, or acting without being seen, nevertheless produces very visible effects. But breath, it is acknowledged, is a material cause; it is allowed to be air modified; it is not, therefore, a simple or pure substance, such as the moderns designate under the name of SPIRIT.

It is rather singular that in the Hebrew, the Greek, and the Latin, the synonymy, or corresponding term for spirit should signify _breath_. The metaphysicians themselves can best say why they have adopted such a word, to designate the substance they have distinguished from matter: some of them, fearful they should not have distinct beings enough, have gone farther, and compounded man of three substances, BODY, SOUL, and INTELLECT.

Although the word _spirit_ is so very ancient among men, the sense attached to it by the moderns is quite new: the idea of spirituality, as admitted at this day, is a recent production of the imagination. Neither PYTHAGORAS nor PLATO, however heated their brain, however decided their taste for the marvellous, appear to have understood by spirit an immaterial substance, or one without extent, devoid of parts; such as that of which the moderns have formed the human soul, the concealed author of motion. The ancients, by the word spirit, were desirous to define matter of an extreme subtilty, of a purer quality than that which acted grossly on our senses. In consequence, some have regarded the soul as an ethereal substance; others as igneous matter; others again have compared it to light. DEMOCRITUS made it consist in motion, consequently gave it a manner of existence. ARISTOXENES, who was himself a musician, made it harmony. ARISTOTLE regarded the soul as the moving faculty, upon which depended the motion of living bodies.

The earliest doctors of Christianity had no other idea of the soul, than that it was material. TERTULLIAN, ARNOBIUS, CLEMENT of ALEXANDRIA, ORIGEN, SAINT JUSTIN, IRENAEUS, have all of them discoursed upon it; but have never spoken of it other than as a corporeal substance--as matter. It was reserved for their successors at a great distance of time, to make the human soul and the soul of the world _pure spirits_; that is to say, immaterial substances, of which it is impossible they could form any accurate idea: by degrees this incomprehensible doctrine of spirituality, conformable without doubt to the views of those who make it a principle to annihilate reason, prevailed over the others: But it might be fairly asked, if the pretended proofs of this doctrine owe themselves to a man, who on a much more comprehensible point has been proved in error; if, on that which time has shewn was accessible to man's reason, the great champion in support of this dogma was deceived; are we not bound to examine, with the most rigorous investigation, the reasonings, the evidence, of one who was the decided, the proven child of enthusiasm and error? Yet DESCARTES, to whose sublime errors the world is indebted for the Newtonian system, although before him the soul had been considered spiritual, was the first who established that, "_that which thinks ought to be distinguished from matter_;" from whence he concludes rather hastily, that the soul, or that which thinks in man, is a spirit; or a simple indivisible substance. Perhaps it would have been more logical, more consistent with reason, to have said, since man, who is matter, who has no idea but of matter, enjoys the faculty of thought, matter can think; that is, it is susceptible of that particular modification called thought.

However this may be, this doctrine was believed divine, supernatural, because it was inconceivable to man. Those who dared believe even that which was believed before; namely, _that the soul was material_, were held as rash inconsiderate madmen, or else treated as enemies to the welfare and happiness of the human race. When man had once renounced experience; when he had abjured his reason; when he had joined the banner of this enthusiastic novelty; he did nothing more, day after day, than subtilize the delirium, the ravings of his imagination: he pleased himself by continually sinking deeper into the most unfathomable depths of error: he felicitated himself on his discoveries; on his pretended knowledge; in an exact ratio as his understanding became enveloped in the mists of darkness, environed with the clouds of ignorance. Thus, in consequence of man's reasoning upon false principles; of having relinquished the evidence of his senses; the moving principle within him, the concealed author of motion, has been made a mere chimera, a mere being of the imagination, because he has divested it of all known properties; because he has attached to it nothing but properties which, from the very nature of his existence, he is incapacitated to comprehend.

The doctrine of spirituality, such as it now exists, offers nothing but vague ideas; or rather is the absense of all ideas. What does it present to the mind, but a substance which possesses nothing of which our senses enable us to have a knowledge? Can it be truth that a man is able to figure to himself a being not material, having neither extent nor parts, which, nevertheless, acts upon matter without having any point of contact, any kind of analogy with it; and which itself receives the impulse of matter by means of material organs, which announce to it the presence of other beings? Is it possible to conceive the union of the soul with the body; to comprehend how this material body can bind, enclose, constrain, determine a fugitive being which escapes all our senses? Is it honest, is it plain dealing, to solve these difficulties, by saying there is a mystery in them; that they are the effects of a power, more inconceivable than the human soul; than its mode of acting, however concealed from our view? When to resolve these problems, man is obliged to have recourse to miracles or to make the Divinity interfere, does he not avow his own ignorance? When, notwithstanding the ignorance he is thus obliged to avow by availing himself of the divine agency, he tells us, this immaterial substance, this soul, shall experience the action of the element of fire, which he allows to be material; when he confidently says this soul shall be burnt; shall suffer in purgatory; have we not a right to believe, that either he has a design to deceive us, or else that he does not himself understand that which he is so anxious we should take upon his word?

Let us not then be surprised at those subtile hypotheses, as ingenious as they are unsatisfactory, to which theological prejudice has obliged the most profound modern speculators to recur; when they have undertaken to reconcile the spirituality of the soul, with the physical action of material beings, on this incorporeal substance; its re-action upon these beings; its union with the body. When the human mind permits itself to be guided by authority without proof, to be led forward by enthusiasm; when it renounces the evidence of its senses; what can it do more than sink into error? Let those who doubt this, read the metaphysical romances of LEIBNITZ, DESCARTES, MALEBRANCHE, CUDWORTH, and many others: let them coolly examine the ingenious, but fanciful systems entitled _the pre-established harmony of occasional causes; physical pre-motion, &c._

If man wishes to form to himself clear, perspicuous ideas of his soul, let him throw himself back on his experience--let him renounce his prejudices--let him avoid theological conjecture--let him tear the bandages which he has been taught to think necessary, but with which he has been blind-folded, only to confound his reason. If it be wished to draw man to virtue, let the natural philosopher, let the anatomist, let the physician, unite their experience; let them compare their observations, in order to show what ought to be thought of a substance, so disguised, so hidden by absurdities, as not easily to be known. Their discoveries may perhaps teach moralists the true motive-power that ought to influence the actions of man--legislators, the true motives that should actuate him, that should excite him to labour to the welfare of society--sovereigns, the means of rendering their subjects truly happy; of giving solidity to the power of the nations committed to their charge. Physical souls have physical wants, and demand physical happiness. These are real, are preferable objects, to that variety of fanciful chimeras, each in its turn giving place to the other, with which the mind of man has been fed during so many ages. Let us, then, labour to perfect the morality of man; let us make it agreeable to him; let us excite in him an ardent thirst for its purity: we shall presently see his morals become better, himself become happier; his soul become calm and serene; his will determined to virtue, by the natural, by the palpable motives held out to him. By the diligence, by the care which legislators shall bestow on natural philosophy, they will form citizens of sound understandings; robust and well constituted; who, finding themselves happy, will be themselves accessary to that useful impulse so necessary for their soul. When the body is suffering, when nations are unhappy, the soul cannot be in a proper state. _Mens sana in corpore sano_, a sound mind in a sound body, will be always able to make a good citizen.

The more man reflects, the more he will be convinced that the soul, very far from being distinguished from the body, is only the body itself, considered relatively to some of its functions, or to some of the modes of existing or acting, of which it is susceptible whilst it enjoys life. Thus, the soul is man, considered relatively to the faculty he has of feeling, of thinking, of acting in a mode resulting from his peculiar nature; that is to say, from his properties, from his particular organization: from the modifications, whether durable or transitory, which the beings who act upon him cause his machine to undergo.

Those who have distinguished the soul from the body, appear only to have distinguished their brain from themselves. Indeed, the brain is the common center, where all the nerves, distributed through every part of the body, meet and blend themselves: it is by the aid of this interior organ that all those operations are performed which are attributed to the soul: it is the impulse, or the motion, communicated to the nerve, which modifies the brain: in consequence, it re-acts, or gives play to the bodily organs; or rather it acts upon itself, and becomes capable of producing within itself a great variety of motion, which has been designated _intellectual faculties_.

From this it may be seen that some philosophers have been desirous to make a spiritual substance of the brain. It is evidently nothing but ignorance that has given birth to and accredited this system, which embraces so little, either of the natural or the rational. It is from not having studied himself, that man has supposed he was compounded with an agent, essentially different from his body: in examining this body, he will find that it is quite useless to recur to hypothesis for the explanation of the various phenomena it presents to his contemplation; that hypothesis can do nothing more than lead him out of the right road to the information after which he seeks. What obscures this question, arises from this, that man cannot see himself: indeed, for this purpose, that would be requisite which is impossible; namely, that he could he at one and the same moment both within and without himself: he may be compared to an Eolian harp, that issues sounds of itself, and should demand what it is that causes it to give them forth? It does not perceive that the sensitive quality of its chords causes the air to brace them; that being so braced, it is rendered sonorous by every gust of wind with which it happens to come in contact.

When a theologian, obstinately bent on admitting into man two substances essentially different, is asked why he multiplies beings without necessity? he will reply, because _"thought cannot be a property of matter."_ If, then, it be enquired of him, _cannot God give to matter the faculty of thought?_ he will answer, _"no! seeing that God cannot do impossible things!"_ According to his principles, it is as impossible that spirit or thought can produce matter, as it is impossible that matter can produce spirit or thought: it might, therefore, be concluded against him, that the world was not made by a spirit, any more than a spirit was made by the world. But in this case, does not the theologian, according to his own assertion, acknowledge himself to be the true atheist? Does he not, in fact, circumscribe the attributes of the Deity, and deny his power, to suit his own purpose? Yet these men demand implicit belief in doctrines, which they are obliged to maintain by the most contradictory assertions.

The more experience we collect, the more we shall be convinced that the word _spirit_, in its present received usage, conveys no one sense that is tangible, either to ourselves or to those that invented it; consequently cannot be of the least use, either in physics or morals. What modern metaphysicians believe and understand by the word, is nothing more than an _occult_ power, imagined to explain _occult_ qualities and actions, but which, in fact, explains nothing. Savage nations admit of spirits, to account to themselves for those effects, which to them appear marvellous, as long as their ignorance knows not the cause to which they ought to be attributed. In attributing to spirits the phenomena of Nature, as well as those of the human body, do we, in fact, do any thing more than reason like savages? Man has filled Nature with spirits, because he has almost always been ignorant of the true causes of those effects by which he was astonished. Not being acquainted with the powers of Nature, he has supposed her to be animated by a _great spirit_: not understanding the energy of the human frame, he has in like manner conjectured it to be animated by a _minor spirit_: from this it would appear, that whenever he wished to indicate the unknown cause of a phenomena, he knew not how to explain in a natural manner, he had recourse to the word _spirit_. In short, _spirit_ was a term by which he solved all his doubts, and cleared up his ignorance to himself. It was according to these principles that when the AMERICANS first beheld the terrible effects of gunpowder, they ascribed the cause to wrathful spirits, to their enraged divinities: it was by adopting these principles, that our ancestors believed in a plurality of gods, in ghosts, in genii, &c. Pursuing the same track, we ought to attribute to spirits gravitation, electricity, magnetism, &c. &c. It is somewhat singular, that priests have in all ages so strenuously upheld those systems which time has exploded; that they have appeared to be either the most crafty or the most ignorant of men. Where are now the priests of Apollo, of Juno, of the Sun, and a thousand others? Yet these are the men, who in all times have persecuted those who have been the first to give natural explanations of the phenomena of Nature, as witness ANAXAGORAS, ARISTOTLE, GALLILEO, DESCARTES, &c. &c.

CHAP. VIII.

_The Intellectual Faculties derived from the Faculty of Feeling_.

To convince ourselves that the faculties called _intellectual_, are only certain modes of existence, or determinate manners of acting, which result from the peculiar organization of the body, we have only to analyze them; we shall then see that all the operations which are attributed to the soul, are nothing more than certain modifications of the body; of which a substance that is without extent, that has no parts, that is immaterial, is not susceptible.

The first faculty we behold in the living man, and that from which all his others flow, is _feeling_: however inexplicable this faculty may appear, on a first view, if it be examined closely, it will be found to be a consequence of the essence, or a result of the properties of organized beings; the same as _gravity, magnetism, elasticity, electricity_, &c. result from the essence or nature of some others. We shall also find these last phenomena are not less inexplicable than that of feeling. Nevertheless, if we wish to define to ourselves a clear and precise idea of it, we shall find that feeling is a particular manner of being moved--a mode of receiving an impulse peculiar to certain organs of animated bodies, which is occasioned by the presence of a material object that acts upon these organs, and transmit the impulse or shock to the brain.

Man only feels by the aid of nerves dispersed through his body; which is itself, to speak correctly, nothing more than a great nerve; or may be said to resemble a large tree, of which the branches experience the action of the root, communicated through the trunk. In man the nerves unite and lose themselves in the brain; that intestine is the true seat of feeling: like the spider in the centre of his web, it is quickly warned of all the changes that happen to the body, even at the extremities to which it sends its filaments and branches. Experience enables us to ascertain, that man ceases to feel in those parts of his body of which the communication with the brain is intercepted; he feels very little, or not at all, whenever this organ is itself deranged or affected in too lively a manner. A proof of this is afforded in the transactions of the Royal Academy of Sciences at Paris: they inform us of a man who had his scull taken off, in the room of which his brain was recovered with skin; in proportion as a pressure was made by the hand on his brain, the man fell into a kind of insensibility, which deprived him of all feeling. BARTOLIN says, the brain of a man is twice as big as that of an ox. This observation had been already made by ARISTOTLE. In the dead body of an idiot dissected by WILLIS, the brain was found smaller than ordinary: he says the greatest difference he found between the parts of the body of this idiot, and those of wiser men, was, that the plexus of the intercostal nerves, which is the mediator between the brain and the heart, was extremely small, accompanied by a less number of nerves than usual. According to WILLIS, the ape is, of all animals, that which has the largest brain, relatively to his size: he is also, after man, that which has the most intelligence: this is further confirmed, by the name he bears in the soil, to which he is indigenous, which is _ourang outang_, or the man beast. There is, therefore, every reason to believe that it is entirely in the brain, that consists the difference, that is found not only between man and beasts, but also between the man of wit, and the fool: between the thinking man, and he who is ignorant; between the man of sound understanding, and the madman: a multitude of experience, serves to prove, that those persons who are most accustomed to use their intellectual faculties, have their brain more extended than others: the same has been remarked of watermen, that they have arms much longer than other men.

However this may be, the sensibility of the brain, and all its parts, is a fact: if it be asked, whence comes this property? We shall reply, it is the result of an arrangement, of a combination, peculiar to the animal: it is thus that milk, bread, wine, change themselves in the substance of man, who is a sensible being: this insensible matter becomes sensible, in combining itself with a sensible whole. Some philosophers think that sensibility is a universal quality of matter: in this case, it would be useless to seek from whence this property is derived, as we know it by its effects. If this hypothesis be admitted, in like manner as two kinds of motion are distinguished in Nature, the one called _live_ force, the other _dead_, or _inert_ force, two sorts of sensibility will be distinguished, the one active or alive, the other inert or dead. Then to animalize a substance, is only to destroy the obstacles that prevent its being active or sensible. In fact, sensibility is either a quality which communicates itself like motion, and which is acquired by combination; or this sensibility is a property inherent in all matter: in both, or either case, an unextended being, without parts, such as the human soul is said to be, can neither be the cause of it nor submitted to its operation; but we may fairly conclude, that all the parts of Nature enjoy the capability to arrive at animation; the obstacle is only in the state, not in the quality. Life is the perfection of Nature: she has no parts which do not tend to it--which do not attain it by the same means. Life in an insect, a dog, a man, has no other difference, than that this act is more perfect, relatively to ourselves in proportion to the structure of the organs: if, therefore, it be asked, what is requisite to animate a body? we reply, it needs no foreign aid; it is sufficient that the power of Nature be joined to its organization.

The conformation, the arrangement, the texture, the delicacy of the organs, as well exterior as interior, which compose men and animals, render their parts extremely mobile, or make their machine susceptible of being moved with great facility. In a body, which is only a heap of fibres, a mass of nerves, contiguous one to the other, united in a common center, always ready to act; in a whole, composed of fluids and solids, of which the parts are in equilibrium, the smallest touching each other, are active in their motion, communicating reciprocally, alternately and in succession, the impression, oscillations, and shocks they receive; in such a composition, it is not surprising that the slightest impulse propagates itself with celerity; that the shocks excited in its remotest parts, make themselves quickly felt in the brain, whose delicate texture renders it susceptible of being itself very easily modified. Air, fire, water, agents the most inconstant, possessing the most rapid motion, circulate continually in the fibres, incessantly penetrate the nerves: without doubt these contribute to that incredible celerity with which the brain is acquainted with what passes at the extremities of the body.

Notwithstanding the great mobility with which man's organization renders him susceptible, although exterior as well as interior causes are continually acting upon him, he does not always feel in a distinct, in a decided manner, the impulse given to his senses: indeed, he does not feel it, until it has produced some change, or given some shock to his brain. Thus, although completely environed by air, he does not feel its action, until it is so modified, as to strike with a sufficient degree of force on his organs; to penetrate his skin, through which his brain is warned of its presence. Thus, during a profound and tranquil sleep, undisturbed by any dream, man ceases to feel. In short, notwithstanding the continued motion that agitates his frame, man does not appear to feel, when this motion acts in a convenient order; he does not perceive a state of health, but he discovers a state of grief or sickness; because, in the first, his brain does not receive too lively an impulse, whilst in the others, his nerves are contracted, shocked, and agitated, with violent, with disorderly motion: these communicating with his brain, give notice that some cause acts strongly upon them--impels them in a manner that bears no analogy with their natural habit: this constitutes, in him, that peculiar mode of existing which he calls _grief_.

On the other hand, it sometimes happens that exterior objects produce very considerable changes on his body, without his perceiving them at the moment. Often, in the heat of battle, the soldier perceives not that he is dangerously wounded, because, at the time, the rapidity, the multiplicity of impetuous motion that assails his brain, does not permit him to distinguish the particular change a part of his body has undergone by the wound. In short, when a great number of causes are simultaneously acting on him with too much vivacity, he sinks under their accumulated pressure,--he swoons--he loses his senses--he is deprived of feeling.

In general, feeling only obtains, when the brain can distinguish distinctly, the impressions made on the organs with which it has communication; it is the distinct shock, the decided modification man undergoes, that constitutes _conscience_. Doctor Clarke, says to this effect: "Conscience is the act of reflecting, by means of which I know that I think, and that my thoughts, or my actions belong to me, and not to another." From this it will appear, that _feeling_ is a mode of being, a marked change, produced on our brain, occasioned by the impulse communicated to our organs, whether by interior or exterior agents, by which it is modified either in a durable or transient manner: it is not always requisite that man's organs should be moved by an exterior object, to enable him to feel that he should be conscious of the changes effected in him: he can feel them within himself by means of an interior impulse; his brain is then modified, or rather he renews within himself the anterior modifications. We are not to be astonished that the brain should be necessarily warned of the shocks, of the impediments, of the changes that may happen to so complicated a machine as the human body, in which, notwithstanding all the parts are contiguous to the brain, and concentrate themselves in this brain, and are by their essence in a continual state of action and re-action.

When a man experiences the pains of the gout, he is conscious of them; in other words, he feels interiorly, that it has produced very marked, very distinct changes in him, without his perceiving, that he has received an impulse from any exterior cause; nevertheless, if he will recur to the true source of these changes, he will find that they have been wholly produced by exterior agents: they have been the consequence, either of his temperament; of the organization received from his parents; of the aliments with which his frame has been nourished; besides a thousand trivial, inappreciable causes, which congregating themselves by degrees produce in him the gouty humour; the effect of which is to make him feel in an acute and very lively manner. The pain of the gout engenders in his brain an idea, so modifies it that it acquires the faculty of representing to itself, of reiterating as it were, this pain when even he shall be no longer tormented with the gout: his brain, by a series of motion interiorly excited, is again placed in a state analogous to that in which it was when he really experienced this pain: but if he had never felt it, he would never have been in a capacity to form to himself any just idea of its excruciating torments.

The visible organs of man's body, by the intervention of which his brain is modified, take the name of _senses_. The various modifications which his brain receives by the aid of these senses, assumes a variety of names. _Sensation_, _perception_, and _idea_, are terms that designate nothing more than the changes produced in this interior organ, in consequence of impressions made on the exterior organs by bodies acting on them: these changes considered by themselves, are called _sensations_; they adopt the term _perception_ when the brain is warned of their presence; _ideas_ is that state of them in which the brain is able to ascribe them to the objects by which they have been produced.

Every _sensation_, then, is nothing more than the shock given to the organs, every _perception_ is this shock propagated to the brain; every _idea_ is the image of the object to which the sensation and the perception is to be ascribed. From whence it will be seen, that if the senses be not moved, there can neither be sensations, perceptions, nor ideas: this will be proved to those, who can yet permit themselves to doubt so demonstrable and striking a truth.

It is the extreme mobility of which man is capable, owing to his peculiar organization, that distinguishes him from other beings that are called insensible or inanimate; the different degrees of this mobility, of which the individuals of his species are susceptible, discriminate them from each other; make that incredible variety, that infinity of difference which is to be found, as well in their corporeal faculties, as in those which are mental or intellectual. From this mobility, more or less remarkable in each human being, results wit, sensibility, imagination, taste, &c.: for the present, however, let us follow the operation of the senses; let us examine in what manner they are acted upon, and are modified by exterior objects:--we will afterwards scrutinize the re-action of the interior organ or brain.

The eyes are very delicate, very movable organs, by means of which the sensation of light or colour is experienced: these give to the brain a distinct perception, in consequence of which, man forms an idea, generated by the action of luminous or coloured bodies: as soon as the eyelids are opened, the retina is affected in a peculiar manner; the fluid, the fibres, the nerves, of which they are composed, are excited by shocks which they communicate to the brain; to which they delineate the images of the bodies from which they have received the impulse; by this means, an idea is acquired of the colour, the size, the form, the distance of these bodies: it is thus that may be explained the mechanism of _sight_.

The mobility and the elasticity of which the skin is rendered susceptible, by the fibres and nerves which form its texture, accounts for the rapidity with which this envelope to the human body is affected when applied to any other body; by their agency, the brain has notice of its presence, of its extent, of its roughness, of its smoothness, of its surface, of its pressure of its ponderosity, &c. Qualities from which the brain derives distinct perceptions, which breed in it a diversity of ideas; it is this that constitutes the _touch_ or _feeling_.

The delicacy of the membrane by which the interior of the nostrils is covered, renders them easily susceptible of irritation, even by the invisible and impalpable corpuscles that emanate from odorous bodies: by these means sensations are excited, the brain has perceptions, and generates ideas: it is this that forms the sense of _smelling_.

The mouth, filled with nervous, sensible, movable, irritable glands, saturated with juices suitable to the dissolution of saline substances, is affected in a very lively manner by the aliments which pass through it for the nourishment of the body; these glands transmit to the brain the impressions received: perceptions are of consequence; ideas follow: it is from this mechanism that results _taste_.

The ear, whose conformation fits it to receive the various impulses of air, diversely modified, communicates to the brain the shocks or sensations; these breed the perception of sound, and generate the idea of sonorous bodies: it is this that constitutes _hearing_.

Such are the only means by which man receives sensations, perceptions, and ideas. These successive modifications of his brain are effects produced by objects that give impulse to his senses; they become themselves causes, producing in his soul new modifications, which are denominated _thought, reflection, memory, imagination, judgment, will, action_; the basis, however, of all these is _sensation_.

To form a precise notion of _thought_, it will be requisite to examine, step by step, what passes in man during the presence of any object whatever. Suppose for a moment this object to be a peach: this fruit makes, at the first view, two different impressions on his eyes; that is to say, it produces two modifications, which are transmitted to the brain, which on this occasion experiences two new perceptions, or has two new ideas or modes of existence, designated by the terms _colour_ and _rotundity_; in consequence, he has an idea of a body possessing roundness and colour: if he places his hand on this fruit, the organ of feeling having been set in action, his hand experiences three new impressions, which are called _softness, coolness, weight_, from whence result three new perceptions in the brain, he has consequently three new ideas: if he approximates this peach to his nose, the organ of _smelling_ receives an impulse, which, communicated to the brain, a new perception arises, by which he acquires a new idea, called _odour_: if he carries this fruit to his mouth, the organ of taste becomes affected in a very lively manner: this impulse communicated to the brain, is followed by a perception that generates in him the idea of _flavour_. In re-uniting all these impressions, or these various modifications of his organs, which it have been consequently transmitted to his brain; that is to say, in combining the different sensations, perceptions, and ideas, that result from the impulse he has received, he has an idea of a whole, which he designates by the name of a peach, with which he can then occupy his thoughts.

From this it is sufficiently proved that thought has a commencement, a duration, an end; or rather a generation, a succession, a dissolution, like all the other modifications of matter; like them, thought is excited, is determined, is increased, is divided, is compounded, is simplified, &c. If, therefore, the soul, or the principle that thinks, be indivisible; how does it happen, that this soul has the faculty of memory, or of forgetfulness; is capacitated to think successively, to divide, to abstract, to combine, to extend its ideas, to retain them, or to lose them? How can it cease to think? If forms appear divisible in matter, it is only in considering them by abstraction, after the method, of geometricians; but this divisibility of form exists not in Nature, in which there is neither a point, an atom, nor form perfectly regular; it must therefore be concluded, that the forms of matter are not less indivisible than thought.

What has been said is sufficient to show the generation of sensations, of perceptions, of ideas, with their association, or connection in the brain: it will be seen that these various modifications are nothing more than the consequence of successive impulses, which the exterior organs transmit to the interior organ, which enjoys the faculty of thought, that is to say, to feel in itself the different modifications it has received, or to perceive the various ideas which it has generated; to combine them, to separate them, to extend them, to abridge them, to compare them, to renew them, &c. From whence it will be seen, that thought is nothing more than the perception of certain modifications, which the brain either gives to itself, or has received from exterior objects.

Indeed, not only the interior organ perceives the modifications it receives from without, but again it has the faculty of modifying itself; of considering the changes which take place in it, the motion by which it is agitated in its peculiar operations, from which it imbibes new perceptions and new ideas. It is the exercise of this power to fall back upon itself, that is called _reflection_.

From this it will appear, that for man to think and to reflect, is to feel, or perceive within himself the impressions, the sensations, the ideas, which have been furnished to his brain by those objects which give impulse to his senses, with the various changes which his brain produced on itself in consequence.

_Memory_ is the faculty which the brain has of renewing in itself the modifications it has received, or rather, to restore itself to a state similar to that in which it has been placed by the sensations, the perceptions, the ideas, produced by exterior objects, in the exact order it received them, without any new action on the part of these objects, or even when these objects are absent; the brain perceives that these modifications assimilate with those it formerly experienced in the presence of the objects to which it relates, or attributes them. Memory is faithful, when these modifications are precisely the same; it is treacherous, when they differ from those which the organs have exteriorly experienced.