In short, herein seems to lie the difference between idiots and madmen, that madmen put wrong ideas together, and so make wrong propositions, but argue and reason right from them: but idiots make very few or no propositions, and reason scarce at all.
John LockeIt is hard to know what other way men can come to truth, to lay hold of it, if they do not dig and search for it as for gold and hid treasure; but he that does so, must have much earth and rubbish, before he gets the pure metal; sand, and pebbles, and dross usually lie blended with it, but the gold is nevertheless gold, and will enrich the man that employs his pains to seek and separate it.
John LockeWhosoever is found variable, and changeth manifestly without manifest cause, giveth suspicion of corruption: therefore, always, when thou changest thine opinion or course, profess it plainly, and declare it, together with the reasons that move thee to change.
John Locke