Those scholars and their peers cited this proof only against whoever posits an essence that is idle—one that at first performs no act and then suddenly acts without any newly arising cause. They assert, “The intellect knows by necessity that a contingent event without a cause is impossible. Therefore, if you say that it occurred by virtue of another contingent cause, the very same reasoning that applied to the first case applies to the second, and you will finally be forced to affirm an event with no cause at all.”

Moreover, the argument rests on the impossibility of an infinite regress of efficient causes, and all rational people agree that such a regress is impossible.

It is answered, first of all, that the argument just mentioned entails neither of those conclusions. Rather, it rests on the impossibility of an infinite regress in the effects that proceed from the Necessary Existent, while the philosophers deem such a regress permissible.

In reality, these philosophers claimed that the celestial spheres and other particular entities are eternal without beginning, whereas their opponents maintained that even the very genus of acting and being acted upon is impossible from all eternity.

Accordingly, the philosophers argued that it is impossible for one who was not an agent to become an agent without a newly arisen cause; yet an event can occur only through an agent, and at that point there is no agent. Hence the statement amounts to: “He is not an agent until He becomes an agent, and He does not become an agent until He becomes an agent.” From one angle this is circular, and from another it produces an infinite regress.

It is, in fact, a regress in His very being an agent, and thus belongs to the regress of efficient causes; yet