Man has occasion for truth; it consists in a knowledge of the true relations he has with those beings competent to have an influence on his welfare; these relations are to be known only by experience: without experience there can be no reason; without reason man is only a blind creature, who conducts himself by chance. But, how is he to acquire experience upon ideal objects, which his senses neither enable him to know nor to examine? How is he to assure himself of the existence, how ascertain the qualities of beings he is not able to feel? How can he judge whether there objects be favorable or prejudicial to him? How is he to know, without the evidence of his senses, what he ought to love, what he should hate, what to seek after, what to shun, what to do, what to leave undone? It is, however, upon this knowledge that his condition in this world rests; it is upon this knowledge that morals is founded. From whence it may be seen, that, by causing him to blend vague metaphysical notions with morals, or the science of the certain and invariable relations which subsist between mankind; or by weakly establishing them upon chimerical ideas, which have no existence but in his imagination; these morals, upon which the welfare of society so much depends, are rendered uncertain, are made arbitrary, are abandoned to the caprices of fancy, are not fixed upon any solid basis.
Beings essentially different by their natural organization, by the modifications they experience, by the habits they contract, by the opinions they acquire, must of necessity think differently. His temperament, as we have seen, decides the mental qualities of man: this temperament itself is diversely modified in him: from whence it consecutively follows, his imagination cannot possibly be the same; neither can it create to him the same images. Each individual is a connected whole, of which all the parts have a necessary correspondence. Different eyes must see differently, must give extremely varied ideas of the objects they contemplate, even when these objects are real. What, then, must be the diversity of these ideas, if the objects meditated upon do not act upon the senses? Mankind have pretty nearly the same ideas, in the gross, of those substances that act upon his organs with vivacity; he is sufficiently in unison upon some qualities which he contemplates very nearly in the same manner; I say, very nearly, because the intelligence, the notion, the conviction of any one proposition, however simple, however evident, however clear it may be supposed, is not, nor cannot be, strictly the same, in any two men. Indeed, one man not being another man, the first cannot, for example, have rigorously and mathematically the same notion of unity as the second; seeing that an identical effect cannot be the result of two different causes. Thus, when men are in accord in their ideas, in their modes of thinking, in their judgment, in their passions, in their desires, in, their tastes, their consent does not arise from their seeing or feeling the same objects precisely in the same manner, but pretty nearly; language is not, nor cannot be, sufficiently copious to designate the vast variety of shades, the multiplicity of imperceptible differences, which is to be found in their modes of seeing and thinking. Each man, then, has, to say thus, a language which is peculiar to himself alone, and this language is incommunicable to others. What harmony, what unison, then, can possibly exist between them, when they discourse with each other, upon objects only known to their imagination? Can this imagination in one individual ever be the same as in another? How can they possibly understand each other, when they assign to those objects qualities that can only be attributed to the particular manner in which their brain is affected.
For one man to exact from another that he shall think like himself, is to insist that he shall be organized precisely in the same manner—that he shall have been modified exactly the same in every moment of his existence: that he shall have received the same temperament, the same nourishment, the same education: in a word, that he shall require that other to be himself. Wherefore is it not exacted that all men shall have the same features? Is man more the master of his opinions? Are not his opinions the necessary consequence of his Nature, and of those peculiar circumstances which, from his infancy, have necessarily had an influence upon his mode of thinking, and his manner of acting? If man be a connected whole, whenever a single feature differs from his own, ought he not to conclude that it is not possible his brain can either think, associate ideas, imagine, or dream precisely in the same manner with that other.
The diversity in the temperament of man, is the natural, the necessary source of the diversity of his passions, of his taste, of his ideas of happiness, of his opinions of every kind. Thus, this same diversity will be the fatal source of his disputes, of his hatreds, of his injustice, every time he shall reason upon unknown objects, but to which he shall attach the greatest importance. He will never understand either himself or others, in speaking of a spiritual soul, or of immaterial substances distinguished from Nature; he will, from that moment, cease to speak the same language, and he will never attach the same ideas to the same words. What, then, shall be, the common standard that shall decide which is the man that thinks with the greatest justice? What the scale by which to measure who has the best regulated imagination? What balance shall be found sufficiently exact to determine whose knowledge is most certain, when he agitates subjects, which experience cannot enable him to examine, that escape all his senses, that have no model, that are above reason? Each individual, each legislator, each speculator, each nation, has ever formed to himself different ideas of these things; each believes, that his own peculiar reveries ought to be preferred to those of his neighbours; which always appear to him an absurd, ridiculous, and false as his own can possibly have appeared to his fellow; each clings to his own opinion, because each retains his own peculiar mode of existence; each believes his happiness depends upon his attachment to his prejudices, which he never adopts but because he believes them beneficial to his welfare. Propose to a man to change his religion for yours, he will believe you a madman; you will only excite his indignation, elicit his contempt; he will propose to you, in his turn, to adopt his own peculiar opinions; after much reasoning, you will treat each other as absurd beings, ridiculously opiniated, pertinaciously stubborn: and he will display the least folly, who shall first yield. But if the adversaries become heated in the dispute, which always happens, when they suppose the matter important, or when they would defend the cause of their own self-love; from thence their passions sharpen, they grow angry, quarrels are provoked, they hate each other, and end by reciprocal injury. It is thus, that for opinions, which no man can demonstrate, we see the Brahmin despised; the Mahommedan hated; the Pagan held in contempt; that they oppress and disdain each with the most rancorous animosity: the Christian burns the Jew at what is called an auto-de-fe, because he clings to the faith of his fathers: the Roman Catholic condemns the Protestant to the flames, and makes a conscience of massacring him in cold blood: this re-acts in his turn; sometimes the various sects of Christians league together against the incredulous Turk, and for a moment suspend their own bloody disputes that they may chastise the enemies to the true faith: then, having glutted their revenge, return with redoubled fury, to wreak over again their infuriated vengeance on each other.
If the imaginations of men were the same, the chimeras which they bring forth would be every where the same; there would be no disputes among them on this subject, if they all dreamt in the same manner; great numbers of human beings would be spared, if man occupied his mind with objects capable of being known, of which the existence was proved, of which he was competent to discover the true qualities, by sure, by reiterated experience. Systems of Philosophy are not subject to dispute but when their principles are not sufficiently proved; by degrees experience, in pointing out the truth and detecting their errors, terminates these quarrels. There is no variance among geometricians upon the principles of their science; it is only raised, when their suppositions are false, or their objects too much complicated. Theologians find so much difficulty in agreeing among themselves, simply, because, in their contests, they divide without ceasing, not known and examined propositions, but prejudices with which they have been imbued in their youth—in the schools—by each other's books, &c. They are perpetually reasoning, not upon real objects, of which the existence is demonstrated, but upon imaginary systems of which they have never examined the reality; they found these disputes, not upon averred experience, or constant facts, but upon gratuitious suppositions, which each endeavours to convince the other are without solidity. Finding these ideas of long standing, that few people, refuse to admit them, they take them for incontestible truths, that ought to be received merely upon being announced; whenever they attach great importance to them, they irritate themselves against the temerity of those who have the audacity to doubt, or even to examine them.
If prejudice had been laid aside, it would perhaps have been discovered that many of those objects, which have given birth to the most shocking, the most sanguinary disputes among men, were mere phantoms; which a little examination would have shown to be unworthy their notice: the priests of Apollo would have been harmless, if man had examined for himself, without prejudice, the tenets they held forth: he would have found, that he was fighting, that he was cutting his neighbour's throat, for words void of sense; or, at the least, he would have learned to doubt his right to act in the manner he did; he would have renounced that dogmatical, that imperious tone he assumed, by which he would oblige his fellow to unite with him in opinion. The most trifling reflection would have shewn him the necessity of this diversity in his notions, of this contrariety in his imagination, which depends upon his Natural conformation diversely modified: which necessarily has an influence over his thoughts, over his will, and over his actions. In short, if he had consulted morals, if he had fallen back upon reason, every thing would have conspired to prove to him, that beings who call themselves rational, were made to think variously; on that account were designed to live peaceable with each other, to love each other, to lend each other mutual succours whatever may be their opinions upon subjects, either impossible to be known, or to be contemplated under the same point of view: every thing would have joined in evidence to convince him of the unreasonable tyranny, of the unjust violence, of the useless cruelty of those men of blood, who persecute, who destroy mankind, in order that they may mould him to their own peculiar opinions; every thing would have conducted mortals to mildness, to indulgence, to toleration; virtues, unquestionably of more real importance, much more necessary to the welfare of society, than the marvellous speculations by which it is divided, by which it is frequently hurried on to sacrifice to a maniacal fury, the pretended enemies to these revered flights of the imagination.
From this it must be evident, of what importance it is to morals to examine the ideas, to which it has been agreed to attach so much worth; to which man is continually sacrificing his own peculiar happiness; to which he is immolating the tranquillity of nations, at the irrational command of fanatical cruel guides. Let him fall back on his experience; let him return to Nature; let him occupy himself with reason; let him consult those objects that are real, which are useful to his permanent felicity; let him study Nature's laws; let him study himself; let him consult the bonds which unite him to his fellow mortals; let him examine the fictitious bonds that enchain him to the most baneful prejudices. If his imagination must always feed itself with illusions, if he remains steadfast in his own opinions, if his prejudices are dear to him, let him at least permit others to ramble in their own manner, or seek after truth as best suits their inclination; but let him always recollect, that all the opinions—all the ideas—all the systems—all the wills—all the actions of man, are the necessary consequence of his nature, of his temperament, of his organization, and of those causes, either transitory or constant, which modify hint: in short, that man is not more a free agent to think than to act: a truth that will be again proved in the following chapter.