Ch. 19 "The Infinite Power of God" from the "Compendium of Theology" by St. Thomas Aquinas

Caput 19 Quod Deus est infinitae virtutis

CHAPTER 19 INFINITE POWER OF GOD

Hinc etiam apparet Deum infinitae virtutis esse. Virtus enim consequitur essentiam rei: nam unumquodque secundum modum quo est, agere potest. Si igitur Deus secundum essentiam infinitus est, oportet quod eius virtus sit infinita.

The further inference is drawn that God is infinite in power. For power is consequent upon a thing’s essence; anything whatever possesses a power of activity consonant with its manner of being. Therefore, if God is infinite in His essence, His power must be infinite.

Hoc etiam apparet, si quis rerum ordinem diligenter inspiciat. Nam unumquodque quod est in potentia, secundum hoc habet virtutem receptivam et passivam; secundum vero quod actu est, habet virtutem activam. Quod igitur est in potentia tantum, scilicet materia prima, habet virtutem infinitam ad recipiendum, nihil de virtute activa participans; et supra ipsam quanto aliquid formalius est, tanto id abundat in virtute agendi: propter quod ignis inter omnia elementa est maxime activus. Deus igitur, qui est actus purus, nihil potentialitatis permixtum habens, in infinitum abundat in virtute activa super alia.

This is clear to anyone who will inspect the order of things. Whatever is in potency, is thereby endowed with receptive and passive power; and so far as a thing is in act, it possesses active power. Hence what is exclusively in potency, namely, prime matter, has an unlimited power of receptivity, but has no part in active power. And in the scale of being above matter, the more a thing has of form, the more it abounds in the power of acting. This is why fire is the most active of all the elements. Therefore God, who is pure act without any admixture of potency, infinitely abounds in active power above all things.