A Letter Concerning Toleration by John Locke was originally published in 1689. Its initial publication was in Latin, though it was immediately translated into other languages. In this "letter" addressed to an anonymous "Honored Sir" (actually Locke's close friend Philip von Limborch, who published it without Locke's knowledge) Locke argues for a new understanding of the relationship between religion and government. One of the founders of Empiricism, Locke develops a philosophy that is contrary to the one expressed by Thomas Hobbes in Leviathan, primarily because it supports toleration for various Christian denominations. Locke's work appeared amidst a fear that Catholicism might be taking over England, and responds to the problem of religion and government by proposing toleration as the answer.
— Excerpted from Wikipedia, the free encyclopedia.