"I think I may say that of all the men we meet with, nine parts of ten are what they are, good or evil, useful or not, by their education."
Locke's opening sentence of his essay defines the rest of his thinking, stating his tabula rasa (blank slate) theory: that men are born with a "blank slate" of a mind that is shaped by experience rather than inborn virtue. Locke's opening statement reinforces this philosophy, saying that whether men are "useful" or not, whether they are "good or evil", depends almost entirely on how they were educated.
"The little and almost insensible impressions on our tender infancies have very important and lasting consequences."
Almost a predecessor to modern theories on child psychology, John Locke argues that the mind is especially malleable when younger; therefore, it is important that children be around good influences and start receiving a good education early.
"Virtue is that a man is able to deny himself his own desires, cross his own inclinations, and purely follow what reason directs as best, though the appetite lean the other way."
Much of Locke's essay revolves around instilling virtue into children and adults alike. Here, he defines virtue essentially as restraint of one's animal desires and the ability to follow logic. He argues that education from a young age will allow men to be able to have greater control of themselves.