Prejudice, a false judgment made by the mind about the nature of things after an insufficient exercise of the intellectual faculties, this unhappy fruit of ignorance thwarts the understanding, blinds and imprisons it.
William James said:
- As a rule we disbelieve all the facts and theories for which we have no use. A great many people think they are thinking when they are really rearranging their prejudices. Balanced Politics
- I meant to be uncommonly clever in taking so decided a dislike to him, without any reason. It is such a spur to one's genius, such an opening for wit to have a dislike of that kind. One may be continually abusive without saying any thing just. 
Prejudices, says Bacon, the man who has meditated the most on this subject, are just so many spectres and phantoms sent to earth by an evil genius in order to torment men; but they are a kind of infectious illness which, like all epidemic diseases, primarily attacks the people, women, children, and old men, and which yields to nothing but maturity and reason.
Prejudice is not always a matter of judgment's being taken by surprise when shrouded in darkness or seduced by false gleams of light; it also emanates from the unfortunate inclination of the mind to go astray, which plunges it into error despite any resistance; for the human mind, far from resembling that faithful crystal whose surface receives rays and transmits them without alteration, is much more like a kind of magic mirror, which distorts objects, and reflects only shadows or monsters.
Prejudices, those idols of the mind, originate either from the nature of the understanding, which endows everything with an intellectual existence, or from the preoccupation of the judgment, which stems in turn either from the obscurity of ideas or the diversity of impressions derived from the disposition of the senses, or from the influence of the passions, always mobile and changing.
There are universal prejudices, and ones, so to speak, that are hereditary in human beings, so strong is the desire for reasons that affirm them. A man sees a fact of nature, attributes it to a certain cause because he prefers to err rather than to doubt; in vain does experience expose the falsehood of his conjectures, the first opinion prevails. It is this disease of the understanding which encourages superstition and a thousand popular errors. One passenger escapes a shipwreck after making a barbarous vow, while all the others perish in the same storm, despite the most legitimate promises; never mind, it's a miracle, as if nature ought not to have changed course in order to conserve so many victims worthy of her pity, rather than to save one guilty one. But then Providence could be said scarcely to concern itself with the interests of human beings!... The names of the fortunate, as Diagoras said, are engraved in temples, while unanswered prayers are drowned in the depths of the sea. Graves hide the doctor's mistakes, while those who recover publicize their supposed cures. In this manner, any enumeration of facts which supports the affirmative propels us to that conclusion, before we examine those negative facts which destroy or diminish the power of the positive proofs. From thence come the fundamental errors that have corrupted most of the sciences, and which seem to have closed the paths of truth to the human mind forever.
Another weakness of the understanding is its precipitation toward extremes. All is uniform in the course of nature; there's the principle: therefore, the stars all revolve in perfect circles; no more ovals, no more ellipses, concludes prejudice . Nature always acts by the most simple means; there's the general maxim; prejudice applies it to all particular facts, and desires all phenomena to submit to this law. Chemists are so obsessed with their elements that they see nothing but water and fire everywhere, just like those fanatic followers of Cybele, whose madness led them to imagine rivers, cliffs, and burning forests at every step.
There are personal, or temperamental prejudices which vary in mankind according to changes in the constitution of the humors, the strength of habit, and the transformations wrought by age. If a man, imprisoned in a subterranean cave from birth to maturity, were suddenly to emerge into daylight, what a crowd of strange impressions, stimulated by a multitude of objects, would assail all the pathways of his mind! This image that Plato conceived hides a most remarkable truth. For the mind of man is as if imprisoned in the senses, and while the eyes glut themselves on the spectacle of nature, a thousand prejudices are formed in the imagination, and in turn enslave the reason.
There are public, or conventional prejudices, which may be considered the apotheosis of error; such is the prejudice of customs always ancient, fashion always new, and language. An insightful mind cannot develop its ideas in the absence of sufficiently energetic expressions. Definitions convey neither the true idea of things nor the proper way of conceiving them. Objects exist in one manner, we perceive them in another, and we describe them neither as they are, nor as we see them. Our ideas are false images, and our expressions equivocal signs. There are words whose usage is so arbitrary that they become unintelligible. Does anyone have a precise idea of fortune, of virtue, of truth? When will there be a treaty agreeing on the ideal signification of these terms? And in what language could it be written so as to be understood by all men in the same sense? We must wait until nature has formed all minds in the same mold.
Finally, there are prejudices of school or faction, based on incorrect notions, or on false principles of reasoning. Among these can be included certain impossibilities which time appears to have sanctioned; the squaring of the circle and perpetual motion, both chimeras remaining to be discovered. Art can combine, but it cannot create anew; the imperturbable order of nature derails the projects and endeavors of men.
Classical axioms lead minds astray: most men don't know how to think differently from others, and if they dared to, how many obstacles would need to be overcome in order to find efficient means to teach them? Think only of how one group, with despotic jealousy, would treat as an enemy and fomenter of faction anyone who failed to do battle for its doctrine, under its insignia, and with its weapons! It is this spirit of zealotry that for a long time has halted the progress of human knowledge and continues to halt it today. Having given Aristotle a kind of supremacy in the schools, the Theologians arrogated to themselves the exclusive right to understand and interpret him, and fabricated a profane conglomeration of revealed and natural truths by subjecting them to the same method. By a process of mutual explanation, reason and faith lent one another a feeble and destructive support, which confused the limits of each kind of notions: thus was born the intestine war between Philosophers and Theologians, which will perhaps last until ignorance and barbarism emerge once again from the dens of the North to swallow up all the quarrels of learned men in the ruin of empires.
The sources of prejudices are also to be found in the passions; so much does interest impose on the understanding that it never looks at anything with a dry and indifferent eye. What pleases us is always true, just, useful, solid, and reasonable. To appease vanity or to flatter laziness, what is difficult is regarded as useless or impossible. Impatience fears the delays of examination; ambition can content itself neither with a moderate experience nor a mediocre success; pride disdains the details of experience and wishes to leap with one bound across the border between tentative and conclusive truths; the sense of propriety forces us to avoid certain problematic subjects; in sum, the understanding is incessantly halted in its course, or disturbed in its judgments.
The senses deceive us if we judge only from the impression of objects, which varies according to the disposition of our organs. The objects that are most significant frequently make only faint impressions, and unhappily for us, the mechanism of all motion depends on those delicate springs which escape our notice.
Each man constructs in his brain a small universe, of which he is the center, and around which revolve all the opinions that intersect, vanish, diverge or converge at the whim of the great mover, which is self-love. Truth occasionally shines out among these confused notions that collide with one another; but it passes by in an instant, as the sun does at the point of noon, in such a manner that we perceive it without being able to take hold of it or follow its course.
One of the prejudices of self-love is to believe that man is the uniquely cherished son of nature, the most perfect result of her works. We suppose that a more beautiful animal could not be made, nor anything more marvelous than the productions of art; hence came that amusing heresy of the anthropomorphites, those pious hermits who doubtless destroyed their faces, believing that they could not honor God sufficiently without giving him a human countenance.
Let man then rid himself of his prejudices, and approach nature with the pure eyes and uncorrupted sentiments that a modest virgin would inspire; he will contemplate her in all her beauty, worthy of all the joy he finds in the details of her charms.