The principal follower and interpreter of Leibniz. Wolff was primarily a mathematician, but renowned as a systematic philosopher, supposing that all the necessary tenets of metaphysics are derivable from the principle of sufficient reason and the principle of identity (Leibniz's law). He was exiled from his university, Halle, in 1723 through the hostile influence of the pietists, but recalled by Frederick II in 1740. In 1743 he became Chancellor of the university. In his most important work, Philosophia Prima sive Ontologia (‘First Philosophy or Ontology’), Wolff gave a systematic ontology along scholastic lines, fusing elements from the systems of Leibniz and Descartes. His system was enormously influential in Germany until well into the 19th century. Kant's teacher Martin Knutzen was a Wolffian, and it was only after he had taught Wolff's system for many years that Kant's ‘dogmatic slumbers’ were shattered by Hume.