The Catholic Encyclopedia explains the difference between the Aristotelian and Eastern conceptions of the procession of the Second Person:
In Aristotelean philosophy perfection is always conceived statically. No action, transient or immanent, can proceed from any agent unless that agent, as statically conceived, possesses whatever perfection is contained in the action. The Alexandrine standpoint was other than this. To them perfection must be sought in dynamic activity. God, as the supreme perfection, is from all eternity self-moving, ever adorning Himself with His own attributes
I’ve been repeating for years that the first sentence is false: my proof was Aristotle’s own account of what act is:
Our meaning [of "act" or energia / entelekia] can be seen in the particular cases by induction, and we must not seek a definition of everything but be content to grasp >the analogy, that it is as that which is building is to that which is capable of building, and the waking to the sleeping, and that which is seeing to that which has its eyes shut but has sight, and that which has been shaped out of the matter to the matter, and that which has been wrought up to the unwrought. Let actuality be defined by one member of this antithesis, and the potential by the other.
Note that, while Aristotle gives four examples of act or energia, only one of them is a static thing, that is, a statue. All others are activities. And so Aristotle clearly wants to make a word that denotes both dynamic perfections (seeing, walking, etc.) and static ones (a statue, a house), that is, a word that speaks of perfection in whatever mode it comes. The Encyclopedia article, however, raises a different point: even if it is true that act denotes both static and dynamic perfections, it is still the case that Aristotle wants to found both of these perfections in the static perfection of an agent, namely, on the form. So far so good, but the next step makes all the difference. Consider U, which is defined as the fact that a form underlies or gives rise to an activity, that is, the fact that things act according to their forms. Is U a perfection? By Aristotle’s own premises, its pretty easy to argue that it isn’t: operation is the perfection of an agent (the whole teaching on act, and even Aristotle’s ethical doctrine rests on this). Operation is more perfect than form, and so U is a mode in which the superior is conditioned by the inferior, that is, a way in which a potency limits an actuality. It follows from this that pure act is pure operation, that is, an operation from which we deny an acting subject. Just as contemporary physics, in denying aether, came to see light as a wave in which nothing was waving, so too theology, by fully unfolding the notion of act, comes to see God as an activity in which no one is acting. There are all sorts of ways to misunderstand this, of course, though there are just as many ways to misunderstand the claim that God is a being that performs divine acts. It’s a radical teaching though, and, at least as the Catholic Encyclopedia presents it, it’s one that even the East didn’t fully come to terms with. to speak of God “ever adorning himself with his own attributes” is only a modest move towards fully recognizing the consequences of the primacy of operation over form or substance.