Ethics part 1: PROP. 26. A thing which is conditioned to act in a particular manner, has >necessarily been thus conditioned by God; and that which has not been conditioned by God >cannot condition itself to act.
Proof.--That by which things are said to be conditioned to act in a particular manner is >necessarily something positive (this is obvious); therefore both of its essence and of its >existence God by the necessity of his nature is the efficient cause (E1P25 and E1P16); this >is our first point. Our second point is plainly to be inferred therefrom. For if a thing, >which has not been conditioned by God, could condition itself, the first part of our proof >would be false, and this, as we have shown, is absurd.
Why does he think whenever the existence and essence of a thing is determined, a thing cannot act otherwise? Does he think a thing act in a different necessarily has a different essence?