It 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 LockeCertainly great persons had need to borrow other men's opinions to think themselves happy; for if they judge by their own feeling, they cannot find it: but if they think with themselves what other men think of them, and that other men would fain be as they are, then they are happy as it were by report, when, perhaps, they find the contrary within.
John LockeAny one reflecting upon the thought he has of the delight, which any present or absent thing is apt to produce in him, has the idea we call love.
John Locke