Summa Theologiae 1, q. 25

Article 1: Is there power in God?
Article 4: Can God bring it about that past things have never existed?
Article 2: Is God’s power infinite?
Article 5: Could God effect things that He does not in fact effect?
Article 3: Is God omnipotent?
Article 6: Could God make things better than He does?



 
Article 1: Is there power in God?

The Latin term potentia is used for both passive power (or potentiality), i.e., the capacity of a patient to take on forms that are communicated to it by some agent cause, and for active power, i.e., the power by which an agent acts.  It has already been established that God lacks passive power, since He cannot be acted upon.  Here St. Thomas distinguishes this claim from the truth that God has active power.

Note, however, the reply to objection 2.  Whereas in creatures who are not always acting to bring about a particular effect, there is a distinction between (a) their active power and(b) the exercise of that active power in an action.  The power itself is an entity in the category of quality, whereas the action exists in the patient and bring's some passive power of the patient to actuality.  In God, this distinction has no place, since God does not go from not exercising His power to exercising it.  His action is one with His essence, and His power is, strictly speaking, a principle only of its effect and not of God's action.  (However, this does not entail that what He effects outside Himself is likewise eternal, since His action determines the topological structure of time, including the question of whether or not time itself, and everything in time, has a beginning.)  

Article 2: Is God’s power infinite?

Article 3: Is God omnipotent?

Article 4: Can God bring it about that past things have never existed?

Article 5: Could God effect things that He does not in fact effect?

Article 6: Could God make things better than He does?