1. _His Early Training_ (1685–1707). Nothing is known of Berkeley’s early years, except that he was born in Kilkenny, Ireland. He was educated at the Eton of Ireland, the Kilkenny school, where Swift had been a pupil; and it is known that one of Berkeley’s schoolmates was Thomas Prior. Berkeley entered Trinity College, Dublin, at fifteen, and graduated at nineteen. Scholasticism was still influential at Trinity, but new sciences, such as botany, chemistry, and anatomy, had been added to the curriculum. There, too, the young Berkeley found that Locke’s _Essay_ was much discussed, and that Newton, Boyle, Malebranche, Descartes, and Leibnitz were widely read. From this early date Berkeley began to keep a book of his own philosophical reflections, calling it his _Commonplace Book_. From it and from his philosophy it would appear that Locke and Malebranche were the most powerful philosophical influences upon him. 2. _As Author_ (1707–1721). Berkeley remained at Dublin as tutor and fellow five years after his graduation. In 1709 he was ordained deacon in the English church. He published two mathematical tracts in 1707, his _Theory of Vision_ in 1709, his _Principles of Human Knowledge_ in 1710. The _Theory of Vision_ and the _Principles of Human Knowledge_ were practically a statement of his philosophy. They have been compared thus: the _Theory of Vision_ teaches that “all that we see is our sensation”; the _Principles of Human Knowledge_ teaches that “all that exists is our knowledge.” Berkeley then went to London, where he was admitted to the court of Queen Anne and also to the circle that included Steele, Swift, Addison, and Pope. Berkeley showed himself humble, wise, considerate, and unselfish, and although he was shocked at the court life, he on his side charmed every one whom he met. He wanted to make his idealism better understood, and so he published it in the form of a dialogue between a realist and an idealist. This publication was called _Three Dialogues between Hylas and Philonous_ (1713). He then made two journeys to the Continent――1713–1714 and 1716–1720――and spent much of the time in Italy, where he absorbed its literature. The South Sea swindle turned him to economics, and in 1721 he published an _Essay toward Preventing the Ruin of Great Britain_. 3. _As Priest and Missionary_ (1721–1753).