Charles Darwin in On the Origin of Species by Means of Natural Selection: Or, The Preservation of Favored Races in the Struggle for Life (Appleton: 1882), p. 2.
No one can feel more sensible than I do of the necessity of hereafter publishing in detail all the facts, with references, on which my conclusions have been grounded; and I hope in a future work to do this. For I am well aware that scarcely a single point is discussed in this volume on which facts cannot be adduced, often apparently leading to conclusions directly opposite to those at which I have arrived. A fair result can be obtained only by fully stating and balancing the facts and arguments on both sides of each question and this is here impossible.
But in double-truth as in most other forms of mental eccentricity we must take some notice of ‘the personal equation,’ by which I mean the special differences and idiosyncrasies that exist between one man and another in respect of intellectual conformation. There are intellects, e.g. so intensely, I might say morbidly, synthetic, that they insist on acquiring demonstrated certitude at whatever cost. This type of mind must needs set itself to evolve unity from multiplicity, harmony from dissonance, light from a juxtaposition of shadows, without considering how far its self-imposed task is feasible or how far it is in agreement with the constitution of the universe. In the determination to acquire undoubted conviction, no labour is spared and no expense regarded. Subordinate convictions are ruthlessly thrust aside, objections are ignored, disingenuous methods resorted to, in order to obtain and definitively pronounce on certitude… [Dr. Newman’s] processes are irregular, inconsistent, self-contradictory, of impossible application to any other subject than that of mystical dogmatism. His conclusions, on the other hand, are brilliantly clear, vivid, unmistakable. His mental evolution stands forth like a mountain whose summit is lit up by a warm glow of sunshine, while the sides and base are enshrouded in darkness. Minds of this class appear to me dominated by a sort of religious or spiritual ambition which is just as selfish, audacious, unscrupulous, and unpitying as any other kind of ambition. A man who overturns all reasoning processes, who makes a chaos of human methods, who stultifies the lessons of history for the purpose of boasting a light which to his neighbours is only a deceptive ignis fatuus, is not unlike Napoleon, who forced his way through cruelty and bloodshed to attain a crown. Such men forget that the infallibility, the unity, and harmony they have achieved so recklessly suggest to the more cautious spectator division and dissonance. They forget that their shield has two sides, and if certainty is emblazoned on one, doubt is conspicuously legible on the other, and that the real Skepticism of their methods, the profound distrust of human reason which marks them, is only dimly veiled by the vaunted infallibility of their conclusions.
Erroneous statements and opinions, in their naked deformity, are generally too hideous to win the regard and confidence of men even in their present depraved condition; while the manifestation of what is true, in its simple grandeur and pure light, is often too bright and fair to be agreeable to the eye and the heart of man. The great work which a lover of truth finds to do, is to separate the conglomerate mass of knowledge, or what men call knowledge, into its two component parts, the true and the false. What is false owes all its plausibility and power to its being associated and mingled with what is true. What is true, is rendered dim and uncertain and weak by being blended and confounded with the erroneous. The human mind is like a thrashing-floor. The honest inquirer will be constantly using the fan, to separate the chaff from the wheat.
But it is not the minds of heretics that are deteriorated most, by the ban placed on all inquiry which does not end in the orthodox conclusions. The greatest harm done is to those who are not heretics, and whose whole mental development is cramped, and their reason cowed, by the fear of heresy. Who can compute what the world loses in the multitude of promising intellects combined with timid characters, who dare not follow out any bold, vigorous, independent train of thought, lest it should land them in something which would admit of being considered irreligious or immoral? Among them we may occasionally see some man of deep conscientiousness, and subtile and refined understanding, who spends a life in sophisticating with an intellect which he cannot silence, and exhausts the resources of ingenuity in attempting to reconcile the promptings of his conscience and reason with orthodoxy, which yet he does not, perhaps, to the end succeed in doing. No one can be a great thinker who does not recognize, that as a thinker it is his first duty to follow his intellect to whatever conclusions it may lead. Truth gains more even by the errors of one who, with due study and preparation, thinks for himself, than by the true opinions of those who only hold them because they do not suffer themselves to think.
Truth is as much the first want as it is the first good of mankind: yes, truth in religion, which by giving us high and pure ideas of the Divinity, teaches us that our homage ought to be worthy of it; truth in morality, which without rigour, as without weak indulgence, traces out to men in all situations their respective duties; truth in policy, which by rendering authority more just, and subjects more submissive, protects governments from the passions of the multitude, and the multitude from the tyranny of governments; truth in our tribunals, which makes vice afraid, reassures and comforts the innocent, and conduces to the triumph of justice; truth in education, which by rendering conduct accordant with doctrine, makes teachers to be the models, as well as the masters of infancy and youth; truth in literature and in the arts, which preserves them from the contagion of bad taste, from false ornaments, and from false thoughts; truth in the commerce of life, which by banishing fraud and imposture, warrants the common safety; truth in every thing, truth before every thing, this is that which the whole human race from its inmost soul is ever seeking, so thoroughly convinced are all men that truth is useful and falsehood hurtful. ¶ When the doctrines of truth are universally inculcated, when they have penetrated into all hearts, and when they animate all classes of society, if they should not succeed in applying a remedy to all disorders, they would certainly have the happy effect of arresting the progress of very many; they would become the fruitful sources of generous sentiment and virtuous action; and they would make us feel that truth is the principle of all life to the social body. But if, on the other hand, error should obtain an ascendancy over the minds of men, and more particularly over the minds of those who are called upon to serve as guides and as examples, it will, by corrupting thought, sentiment, and action, become a principle of dissolution and of death.
It is a great mortification to the vanity of man, that his utmost art and industry can never equal the meanest of nature’s productions, either for beauty or value. Art is only the under-workman, and is employed to give a few strokes of embellishment to those pieces, which come from the hand of the master. … Art may make a suit of clothes; but nature must produce a man. … All sentiment is right; because sentiment has a reference to nothing beyond itself, and is always real, wherever a man is conscious of it. But all determinations of the understanding are not right; because they have a reference to something beyond themselves, to wit, real matter of fact; and are not always conformable to that standard. … Beauty is no quality in things themselves: It exists merely in the mind which contemplates them; and each mind perceives a different beauty. One person may even perceive deformity, where another is sensible of beauty; and every individual ought to acquiesce in his own sentiment, without pretending to regulate those of others.
The grounds of those persuasions which are to be found amongst men, so various, different, and wholly contradictory; and yet asserted somewhere or other with such assurance and confidence, that he that shall take a view of the opinions of mankind, observe their opposition, and at the same time consider the fondness and devotion wherewith they are embraced, the resolution and eagerness wherewith they are maintained, may perhaps have reason to suspect, that either there is no such thing as truth at all, or that mankind hath no sufficient means to attain a certain knowledge of it.
I have never contemplated anything higher than the reformation of my own opinions, and basing them on a foundation wholly my own. And although my own satisfaction with my work has led me to present here a draft of it, I do not by any means therefore recommend to every one else to make a similar attempt. Those whom God has endowed with a larger measure of genius will entertain, perhaps, designs still more exalted; but for the many I am much afraid lest even the present undertaking be more than they can safely venture to imitate. The single design to strip one’s self of all past beliefs is one that ought not to be taken by every one. The majority of men is composed of two classes, for neither of which would this be at all a befitting resolution: in the first place, of those who with more than a due confidence in their own powers, are precipitate in their judgments and want the patience requisite for orderly and circumspect thinking; whence it happens, that if men of this class once take the liberty to doubt of their accustomed opinions, and quit the beaten highway, they will never be able to thread the byeway that would lead them by a shorter course, and will lose themselves and continue to wander for life; in the second place, of those who, possessed of sufficient sense or modesty to determine that there are others who excel them in the power of discriminating between truth and error, and by whom they may be instructed, ought rather to content themselves with the opinions of such than trust for more correct to their own Reason.