Human nature with all its infirmities and depravation is still capable of great things. It is capable of attaining to degrees of wisdom and goodness, which we have reason to believe, appear as respectable in the estimation of superior intelligences. Education makes a greater difference between man and man, than nature has made between man and brute. The virtues and powers to which men may be trained, by early education and constant discipline, are truly sublime and astonishing. Newton and Locke are examples of the deep sagacity which may be acquired by long habits of thinking and study.

Letter to Abigail Adams (29 October 1775), published Letters of John Adams, Addressed to His Wife, Vol. 1 (1841), ed. Charles Francis Adams, p. 72