Every man carries about him a touchstone, if he will make use of it, to distinguish substantial gold from superficial glitterings, truth from appearances. And indeed the use and benefit of this touchstone, which is natural reason, is spoiled and lost only by assuming prejudices, overweening presumption, and narrowing our minds.
John LockeReason, if consulted with, would advise, that their children's time should be spent in acquiring what might be useful to them when they come to be men, rather than to have their heads stuff'd with a deal of trash, a great part whereof they usually never do ('tis certain they never need to) think on again as long as they live: and so much of it as does stick by them they are only the worse for.
John LockeIt is practice alone that brings the powers of the mind, as well as those of the body, to their perfection.
John Locke