Gödel first advocated the philosophy of Leibniz and then, since 1959, that of Husserl. Based on research in Gödel's archive, from which a number of unpublished items are presented, we argue that (1) Gödel turned to Husserl in search of a means to make Leibniz' monadology scientific and systematic, and (2) This explains Gödel's specific turn to Husserl's transcendental idealism as opposed to the realism of the earlier Logical Investigations. We then give three examples of concrete influence from Husserl on Gödel's writings.