1. In the two orders of things — those whose existence is that of process and those in whom it is Authentic Being — there is a variety of possible relation to Cause.
Cause might conceivably underly all the entities in both orders or none in either. It might underly some, only, in each order, the others being causeless. It might, again, underly the Realm of Process universally while in the Realm of Authentic Existence some things were caused, others not, or all were causeless. Conceivably, on the other hand, the Authentic Existents are all caused while in the Realm of Process some things are caused and others not, or all are causeless.
Now, to begin with the Eternal Existents:
The Firsts among these, by the fact that they are Firsts, cannot be referred to outside Causes; but all such as depend upon those Firsts may be admitted to derive their Being from them.
And in all cases the Act may be referred to the Essence [as its cause], for their Essence consists, precisely, in giving forth an appropriate Act.