Locke was important in his own day, is important now, and has been important in the interval. He is also important for more than his political philosophy. The two greatest philosophers for our purposes in the seventeenth century are Hobbes and Locke. Hobbes's greatest work was in political philosophy. Locke's was not. Both then and subsequently, Locke has been best known for his great work of epistemology, the Essay Concerning Human Understanding. Born in 1632, the same year as Pufendorf, Locke was already in his late fifties when the Essay was published, and for the rest of his life he was the famous writer of the Essay, which bore his name on the title page.

On this title page also is the date 1690, although the work was in fact published at the end of 1689. Almost simultaneously, Locke published his main work of political philosophy, The Two Treatises on Government. This is also dated 1690 on the title page, but it also in fact appeared in 1689. Here, however, the resemblance ends. The Two Treatises appeared anonymously, and Locke kept his authorship of them a fairly closely guarded secret for the rest of his life. He was not the famous author of the Two Treatises. Also in 1689, and also anonymously, Locke's other main work of political philosophy, the Epistola de Tolerantia appeared. This was rapidly translated into English (although not by Locke himself) as A Letter Concerning Toleration.