Gassendi's residence in Paris and his Dutch travels in the late 1620s were significant not only because they resulted in his decision to expand the scope of the Epicurean project. They also constituted a key period in his development as a historian of philosophy. For just as his earlier encounters with Mersenne had forced him to rethink the consequences of his use of skepticism as a weapon against Aristotle, his new encounters with influential humanists forced him to recognize the importance of other aspects of humanism, especially those aspects involving the creation and use of scholarly libraries. In Paris Gassendi himself succumbed to the attraction of days of endless research in an impressive repository of books and documents, the library of the historian Jacques-Auguste de Thou, which was administered since De Thou's death in 1617 by Pierre and Jacques Dupuy. Mindful of the open-endedness of research in a library containing over 8,000 volumes of printed books and over 1,000 manuscripts – research in which the determinate goal of refuting Aristotle may easily have been subsumed in the investigation of other philosophical systems – Gassendi began to recognize a tacit assumption underlying the humanists' devotion to scholarship. He recognized the tendency of his scholarly friends to assume, on the basis of their research in such libraries, that the whole spectrum of past human cultures could be assembled and analyzed if only scholars would work assiduously enough toward that end.