 An outstanding example of that sort of usefulness, in Arnauld’s view, was Descartes’ argument for the distinction of the soul or mind from the body. Arnauld refers to Descartes as a “Christian philosopher,” echoing Descartes’ own use of the phrase in the letter dedicating the Meditations on First Philosophy to the Faculty of Theology of the Sorbonne, where Descartes says that he carried out the injunction of the Fourth Lateran Council (1512–17) that “Christian philosophers” should try to prove the immateriality of the soul (Descartes, 2:4).