More relatively simple material this week. But it’s going to heat up soon. Review!
 TAKING then as granted the things that were proved in the foregoing Book, let us now proceed to prove that it becomes God to be the source and cause of being to other things.
Notes He means Book 1. Start here.
 For it was shown above by the proof of Aristotle that there is a first efficient cause which we call God. Now an efficient cause brings its effects into being. Therefore God is the cause of being to other things.
 Again. It was shown in the First Book by the argument of the same author, that there is a first immovable mover, which we call God. Now the first mover in any order of movements is the cause of all the movements in that order. Since then many things are brought into being by the movements of the heaven, and since God has been proved to be the first mover in the order of those movements, it follows that God is the cause of being to many things.
Notes Super-condensed review (do not expect to understand everything in this one paragraph). By “change” or “movement” we mean activiation of a potential. Every activation of a potential requires something actual. Every here-and-now secondary cause needs a first or initial here-and-now cause or now activation of any potential could ever happen. God is this First Activator, i.e. He is pure actuality, Being Itself. Every substance is a “mixture” of being and essence. God’s being is His essence. God must provide the ultimate cause of all being.
 Moreover. That which belongs to a thing by its nature, must needs be in that thing universally; as for man to be rational, and for fire to tend upwards. Now it belongs to a being in act that it should enact an effect; for every agent acts according as it is in act. Therefore it is natural to every being in act to enact something existing in act. Now God is being in act, as we proved in the First Book. Therefore it is competent to Him to produce something in act, to which He is the cause of being.
Notes A vase is potentially a pile of shards. The potential-pile cannot act. It requires something actual to actualize the potential-of-being-shards. An example of an actuality: a flying baseball.
 Further. It is a sign of perfection in things of the lower world, that they are able to produce their like, as stated by the Philosopher (4 Meteor.). Now God is supremely perfect, as was proved in the First Book. Therefore it is competent to Him to produce something in act like unto Himself, so that He is the cause of its being.
 Again. It was shown in the First Book that God wills to communicate His being to other things by way of likeness. Now it belongs to the will’s perfection to be the principle of action and movement, as stated in 3 De Anima. Since then God’s will is perfect, it lacks not the power of communicating His being to a thing by way of likeness. And thus He will be the cause of its being…
Notes Given or accepting the prior proofs, it cannot be controversial that God can cause things to be.
 IT follows from this that God is powerful, and that active power is fittingly ascribed to Him.
 For active power is the principle of acting on another as such. Now it becomes God to be the principle of being to other things. Therefore it becomes Him to be powerful.
 Moreover. Just as passive potentiality is consequent upon being in potentiality, so active potency is consequent upon being in act: for a thing is active because it is in act, and passive because it is in potentiality. Now it becomes God to be in act. Therefore active power is becoming to Him.
Notes The vase is in passive potential to being in shards, the baseball is in active potential to busting through the vase. Passive and active, the done to and doer. For a richer and more complete explanation, read this. In God there is no passive potency, but there can be active potency. See paragraph 5 below.
 Again. The divine perfection includes the perfection of all things, as was proved in the First Book. Now active power belongs to the perfection of a thing: since a thing is found to be the more perfect in proportion as it is more powerful. Therefore God cannot be devoid of active power.
 Further. Whatever acts, has the power to act, since that which has not the power to act, cannot possibly act; and what cannot possibly act, of necessity does not act. Now God acts and moves, as was proved above. Therefore He has the power to act; and active but not passive potency is fittingly ascribed to Him.
Notes Thus when we say God is pure act or that God has no potentiality in Him, we mean He is always the doer and not the done-toer. Simple! As in, God is metaphysically simple, i.e. (this is review) has no passive potentiality. The concept of active potentiality is therefore not so straightforward. To God, all of time exists at once; He is outside time. Therefore He does not change.