Set the mind to work, and apply the thoughts vigorously to the business, for it holds in the struggles of the mind, as in those of war, that to think we shall conquer is to conquer.
John LockeUnderstanding like the eye; whilst it makes us see and perceive all things, takes no notice of itself; and it requires art and pains to set it at a distance and make it its own subject.
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 Locke