The only thing that one really knows about human nature is that it changes. Change is the one quality we can predicate of it. The systems that fail are those that rely on the permanency of human nature, and not on its growth and development. The error of Louis XIV was that he thought human nature would always be the same. The result of his error was the French Revolution. It was an admirable result.
Observe how every truth and every error, each a thought of someone's mind, clothes itself with societies, houses, cities, language, ceremonies, newspapers
Delusions, errors and lies are like huge, gaudy vessels, the rafters of which are rotten and worm-eaten, and those who embark in them are fated to be shipwrecked.
The fatal errors of life are not due to man's being unreasonable: an unreasonable moment may be one's finest moment. They are due to man's being logical.
What is this self-inside us, this silent observer, severe and speechless critic, who can terrorize us, and urge us onto futile activity, and in the end, judge us still more severely for the errors into which his own reproaches drove us?
He who gives himself to a lover because he is a good man, and in the hope that he will be improved by his company, shows himself to be virtuous, even though the object of his affection turn out to be a villain, and to have no virtue; and if he is deceived he has committed a noble error. For he has proved that for his part he will do anything for anybody with a view to virtue and improvement, than which there can be nothing nobler.
Extemporaneous speaking should be practised [sic] and cultivated. It is the lawyer's avenue to the public. However able and faithful he may be in other respects, people are slow to bring him business if he cannot make a speech. And yet there is not a more fatal error to young lawyers than relying too much on speech-making. If any one, upon his rare powers of speaking, shall claim an exemption from the drudgery of the law, his case is a failure in advance.
A wild angel had appeared to him, the angel of mortal youth and beauty, an envoy from the fair courts of life, to throw open before him in an instant of ecstasy the gates of all the ways of error and glory.
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.
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?
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.