 The resources of Cartesian philosophy for repudiating skepticism also appealed to Arnauld. Cartesian knowledge is grounded in clear and distinct perceptions of reason alone. Truths delivered by reason alone cannot be doubted unless they are not clear and distinct and thus “confused” in Descartes’ terminology. For Descartes and Arnauld this means that skeptical denials of fundamental truths are merely verbal (Logic, First Discourse 7; also see Lennon 2008: 62–77). The soul surrenders to the truth whenever it is strongly penetrated by it just as eyes see whenever they are open and struck by sunlight (Logic, First Discourse, 8). For example, one who affirms that “It is doubtful that God exists” must fail to clearly and distinctly perceive God. The Logic sets itself against Montaigne and Pyrrhonian skepticism in particular, but also takes frequent opportunities to undercut skeptical threats from materialism and irreligion. Elsewhere, Arnauld wanted to emphasize along with Descartes himself that the latter’s “method of doubt” as presented in the Meditations “should be studied only by very intelligent and well-educated readers” (Replies to fourth set of objections [CSM II, 172]). This restriction was meant to avoid encouraging the very doubts that Descartes introduces as part of the specialized method for attaining certain knowledge.