This paper presents new evidence regarding Hume's stay in La Flèche and attempts to reconstruct the intellectual world in which he wrote A Treatise of Human Nature. The evidence comes from a 1777 manuscript containing the catalogue of the library of the College of La Flèche, where Hume worked, and from a study of the books still extant in that library. Based on this new evidence, I claim a) that La Flèche provided Hume with a rich intellectual environment where he could learn not only about philosophy and classical literature but also get acquainted with the main debates that agitated scholars on the Continent; b) that Hume had access to the works of Sextus and to other important sources on skepticism; and c) that we should pay closer attention to the influence of some less-noticed French sources on Hume's philosophical views.