  But what sense can be made of the doctrine of created truth? By what kind of causality did God create the eternal (necessary) truths? In response to this very question Descartes replied that God did so in just the way that He created everything else, that He is the total and efficient cause not only of the existence of created things, but also of their essence. The eternal truths are just this essence of created things. As before, Descartes did not elaborate his answer, but, once again, he provided enough elsewhere for us to do so. It is clear that for Descartes, as for many other theologically orthodox thinkers, the existence of things results from an unconstrained exercise of God’s omnipotent will to create ex nihilo. What Descartes might be saying, then, is that an eternal truth or essence is also something that is created ex nihilo. The eternal truths might thus be instances of what Descartes called substance.