  But what is the character of these non-actualized possibles? The most natural assumption is that they are like individual substances as characterized by Leibniz in Discourse on Metaphysics §8, that is, as having complete individual concepts. In other words, all individuals (actual or merely possible) have determinate essences. In the case of merely possible individuals, however, their being is contained solely in the divine mind. Consider Leibniz's claim in the Theodicy §189: “In the region of the eternal verities are found all the possibles.” (G VI 229/H 246) And, in §44 of the Monadology, in the middle of his argument for God's necessary existence, Leibniz says, “if there is reality in essences or possibles, or indeed, in eternal truths, this reality must be grounded in something existent and actual, and consequently, it must be grounded in the existence of the necessary being, in whom essence involves existence, that is, in whom possible being is sufficient for actual being.” (G VI 614/AG 218) In other words, there will be determinate essences of some substances that are actualized in the world as well as determinate essences of substances that exist solely in the divine intellect.