John Locke to Charles Mordaunt, 3rd earl of Peterborough between February and March 1690
I must beg leave to own that I differ a little from your Lordship in what you propose; your Lordship would have a thorough scholar, and I think it not much matter whether he be any great scholar or no; if he but understand Latin well, and have a general scheme of the sciences, I think that enough: but I would have him well-bred, well-tempered; a man that having been conversant with the world and amongst men, would have great application in observing the humour and genius of my Lord your son; and omit nothing that might help to form his mind, and dispose him to virtue, knowledge, and industry. This I look upon as the great business of a tutor; this is putting life into his pupil, which when he has got, masters of all kinds are easily to be had; for when a young gentleman has got a relish of knowledge, the love and credit of doing well spurs him on; he will with or without teachers, make great advances in whatever he has a mind to. Mr. Newton learned his mathematics only of himself; and another friend of mine, Greek (wherein he is very well skilled) without a master; though both these studies seem more to require the help of a tutor than almost any other.
(From Locke, John. The Correspondence of John Locke. Ed. E. S. de Beer. 8 vols. Oxford: Oxford University Press, 1976–1989.)