Leibnitz became court councilor and librarian to the Duke of Hanover (Brunswick-Lüneburg). He was involved in a multitude of administrative, historical, and political tasks, and he carried on an enormous correspondence. Among other things he wrote the history of the reigning family, which necessitated his going to Rome and Vienna. In 1684 he published his discovery of the differential calculus, over which arose the celebrated controversy as to whether he or Newton made the prior discovery. In 1686, in his fortieth year, he constructed his philosophical system. However, he showed his affiliation to the coming age by introducing into his system in 1697 the term “monad.” _Nearly all his important works were produced in this period._ In 1700 he founded the Academy of Sciences in Berlin. He was instrumental in the founding of an academy at St. Petersburg, and he planned academies at Dresden and Vienna. =The Three Influences upon the Thought of Leibnitz.= (1) _His Early Classical Studies._ The father of Leibnitz, who was a professor of moral philosophy at Leipsic, died when his son was young. Left much to himself, the boy spent his time in his father’s library. At eight years he had acquired Latin; at twelve he had read Seneca, Pliny, Quintilian, Herodotus, Xenophon, Cicero, Plato, the Roman historians, the Greek and Latin fathers. He became so absorbed in scholastic studies that his friends feared that he would not leave them, “not knowing that my mind could not be satisfied with only one kind of thing.” There can be no question that this scholastic training gave him a first hand and sympathetic appreciation of scholastic philosophy. The Aristotelian conception of cosmic purpose, which he got at this time, never left him. Among the writers of the Natural Science Period he alone returned to Aristotle. He made Aristotle’s teleological cause an integral part of his doctrine. His motto finally became, in his _Theodicy_, “Everything is best in this best of possible worlds.” While for a time he turned from Aristotle to Descartes, in his final construction of his theory he borrowed more from Aristotle.