1638-1715. French Catholic philosopher. He entered the Oratorians* in Paris (1660) where he remained throughout his life. He was ordained priest (1664). His philosophical work concentrated on the relation between faith, reason, and empirical observation, seeking therein to find an accommodation between Catholicism and Cartesian philosophy. De la recherche de la vérité (2 vols., 1674-75), Traité de la nature et de la grace (1680), and Entretiens sur la métaphysique et sur la religion (1688) are his greatest works and embroiled him in constant polemics, with Bossuet, Leibnitz, Fontenelle, and many others. As a scientist he studied insects, mathematics, and color; simultaneously he was a méditatif in the Oratory.