  As with Leibniz and Wolff, Du Châtelet's two primary first principles of knowledge are the PC—‘the basic axiom upon which all truths are founded’, which is consequently the foundation of all certainty (§4)—and the PSR (§8). These two principles operate not by opening up a category of metaphysical truths that are innate to our minds. Rather, they operate by giving universal (perhaps one would want to call these innate)[6] procedures for delineating what is possible from what is impossible, and then for determining what is necessary and what is actual (as opposed to non-actual) from among the range of possibilities. Du Châtelet's first use of the PC, then, is decidedly Wolffian for its task is to separate the impossible from the possible.