Perceptions, by their very nature, must be brought into existence by something new, whereas an eternal, fully-complete cause that necessitates its effect by its very essence is, from pre-eternity, accompanied by that effect—the very product and entailment of its nature. Consequently, none of these motions, volitions, or perceptions can be an effect of such a cause, for all of them are temporal; nor can they necessitate, act upon, or produce it, because temporal events cannot issue from an eternally complete cause. From this it becomes evident that their claim of the world’s eternality is false, and that everything other than God, exalted be He, came into being after previously not existing. For anything that is both eternal and caused could proceed only from a self-necessitating agent whose necessitation is eternal—that is, from an eternally complete cause that entails its effect from pre-eternity.
If, then, there were in the universe anything eternal, the existence of an eternally complete cause would necessarily follow. Yet the existence of such a cause is impossible, for it would entail that temporal events have no agent, whether through an intermediary or without one, since events do not arise from a cause whose completeness is eternal.
Accordingly, everything besides God must either coincide with some temporal events or have temporal events occur within it; and whatever coincides with, or contains, temporal events cannot proceed from an eternally complete cause, for it cannot emerge from the agent devoid of those events, while the events themselves still require an agent.
Thus, affirming the eternity of any part of the cosmos entails positing an eternal cause for it, and positing such a cause results in denying an agent for temporal events—whether one says that from that eternal cause there issues something accompanied by temporal events, or something within which temporal events arise. In either case, temporal events would have no agent, for it is impossible for them to originate from an eternally complete cause. And since the eternity of any part of the world entails positing an eternally complete cause—