Traditionally, there are two models for how God preserves the existence of the universe. The first is creatio originans (originating creation), which suggests that there has been one initial act of creation and God conserves that reality through a temporal duration. Consider the following definition.
D1. God conserves e if and only if God acts upon e to bring about e’s enduring from t until some t* > t through every subinterval of the interval t –> t*.
Thomas Aquinas de-temporalizes creatio ex nihilo. Thus, Thomas is not very concerned with divine conservation as described above since he does not offer a tensed version of creation nor does he differentiate between conservation and creation. Thomas’ model of creatio continuans (continual creation) can therefore be depicted as:
D2. God continuously creates x = def. x is a persistent thing, and, for all t, if x exists at t, then at t God creates x.
Thomas certainly seems to make a commitment to creatio continuans given his doctrine of simplicity (since timeless follows). However, Thomas tries to have the best of both doctrines by suggesting that God acts within creation and creation was within time yet, in turn, adopt a model of timelessness. Thomas argues that the creation of things was in the beginning of time. For Genesis 1 to include, “In the beginning God created heaven and earth” suggests that beginning connotes time.