 Proposition 8 in Leibniz’s outline is: “In order to distinguish the actions of God from those of creatures, it is explained wherein consists the notion of an individual substance” (LA,8). The notion of a substance is, for Leibniz, the notion of a thing that acts. To explain the notion of a created individual substance, therefore, he has to explain the notion of a created agent, which requires that he distinguish correctly between the actions of creatures and the actions of God. Part of Leibniz’s account of the notion of an individual substance is given in Proposition 13: “The individual notion of each person includes once and for all everything that will ever happen to him,” so that “one sees in [that notion] a priori proofs of the truth of each event, that is, why one [event] has occurred rather than another” (LA, 8). The debate between Arnauld and Leibniz begins here. Proposition 13, Arnauld said in his first letter to Leibniz, implies that “once God decided to create Adam, everything that has happened since and will ever happen to the human race was and is obliged to happen with a more than fatal necessity” (LA, 27). For example, given proposition 13, if Adam exists, then necessarily Adam is father of Cain and Abel as sons, grandfather of their children, great-grandfather of their children, etc., and everything that will ever happen to all of them is already determined.