3. _As Philosophical Author_ (1683–1691). The year 1689 divides this period into two important parts. The first part (1683–1689) is not only the period of his exile in Holland, but it is the time in which he is composing and completing his three most important literary works,――_Essay on the Human Understanding_, the two _Treatises on Government_, the three _Epistles on Tolerance_. During the second part (1689–1691) he published these, which was the time immediately following his return to England. Newton’s _Principia_ was published in 1687, and Locke’s _Essay_ in 1690――the one the foundation of modern physical science, the other the beginning of modern psychology. The appearance of these two works together with the Revolution in 1688 makes this point of time an important one in the history of the world. 4. _As Controversialist_ (1691–1704). Locke then began to write upon almost every conceivable subject,――the coining of silver money, the raising of the value of money, the culture of olives, etc. He was also very busy in defending his philosophy against attacks. For him, until 1700 the period was one of controversy. At that time he retired from all activity, and after four years of failing health died in 1704. His period of production was confined to the eleven years between 1689 and 1700. =The Sources of Locke’s Thought.= 1. _His Puritan Ancestry._ The ancestry of Locke is little known, and not much that appears in his personality can be explained by it. Both his father and mother were Puritans, and he seems to have inherited the severe piety, prudent, self-reliant industry, and love of liberty, that were common in English Puritan families of the middle class in the seventeenth century. During the first fourteen years he was schooled by his parents.