No one should be judged by their defects. The great virtues a person has are his or her especially. But their errors are the common weakness of humanity and should never be counted in estimating a person’s character.
When we look at the matter from another point of view, great caution would seem to be required. For the habit of lightly changing the laws is an evil, and, when the advantage is small, some errors both of lawgivers and rulers had better be left; the citizen will not gain so much by making the change as he will lose by the habit of disobedience.
There is no more evil thing in this world than race prejudice, none at all. [...] It justifies and holds together more baseness, cruelty, and abomination than any other sort of error in the world.
Every limited mind demands a certain freedom of expression, and the man who cannot express himself satisfactorily without the stimulation derived from the spirited mode of two centuries ago should certainly be permitted to follow without undue restraint a practice so harmless, so free from essential error, and so sanctioned by precedent, as that of employing in his poetical compositions the smooth and inoffensive allowable rhyme.
Those wretches who never have experienced the sweets of wisdom and virtue, but spend all their time in revels and debauches, sink downward day after day, and make their whole life one continued series of errors.
Were half the power that fills the world with terror, Were half the wealth bestowed on camps and courts, Given to redeem the human mind from error, There were no need of arsenals or forts.
If at times I have thought myself unfortunate, it is because of a confusion, an error. I have mistaken myself for someone else... Who am I really? I am the author of The World as Will and Representation, I am the one who has given an answer to the mystery of Being that will occupy the thinkers of future centuries. That is what I am, and who can dispute it in the years of life that still remain for me?
Eratosthenes's only tools were sticks, eyes, feet, and brains; plus a zest for experiment. With those tools he correctly deduced the circumference of the Earth, to high precision, with an error of only a few percent. That's pretty good figuring for 2200 years ago.
Concepts which have proved useful for ordering things easily assume so great an authority over us, that we forget their terrestrial origin and accept them as unalterable facts. They then become labeled as 'conceptual necessities,' etc. The road of scientific progress is frequently blocked for long periods by such errors.