Objection 1. It would seem that the soul of Christ had omnipotence. For Ambrose [Gloss, Ord.] says on Luke 1:32: "The power which the Son of God had naturally, the Man was about to receive in time." Now this would seem to regard the soul principally, since it is the chief part of man. Hence since the Son of God had omnipotence from all eternity, it would seem that the soul of Christ received omnipotence in time.
Objection 2. Further, as the power of God is infinite, so is His knowledge. But the soul of Christ in a manner had the knowledge of all that God knows, as was said above (Question 10, Article 2). Therefore He had all power; and thus He was omnipotent.
Objection 3. Further, the soul of Christ has all knowledge. Now knowledge is either practical or speculative. Therefore He has a practical knowledge of what He knows, i.e. He knew how to do what He knows; and thus it seems that He can do all things.
On the contrary, What is proper to God cannot belong to any creature. But it is proper to God to be omnipotent, according to Exodus 15:2-3: "He is my God and I will glorify Him," and further on, "Almighty is His name." Therefore the soul of Christ, as being a creature, has not omnipotence.
I answer that, As was said above (2, 1; 10, 1) in the mystery of Incarnation the union in person so took place that there still remained the distinction of natures, each nature still retaining what belonged to it. Now the active principle of a thing follows its form, which is the principle of action. But the form is either the very nature of the thing, as in simple things; or is the constituent of the nature of the thing; as in such as are composed of matter and form.
And it is in this way that omnipotence flows, so to say, from the Divine Nature. For since the Divine Nature is the very uncircumscribed Being of God, as is plain from Dionysius (Div. Nom. v), it has an active power over everything that can have the nature of being; and this is to have omnipotence; just as every other thing has an active power over such things as the perfection of its nature extends to; as what is hot gives heat. Therefore since the soul of Christ is a part of human nature, it cannot possibly have omnipotence.
Reply to Objection 1. By union with the Person, the Man receives omnipotence in time, which the Son of God had from eternity; the result of which union is that as the Man is said to be God, so is He said to be omnipotent; not that the omnipotence of the Man is distinct (as neither is His Godhead) from that of the Son of God, but because there is one Person of God and man.
Reply to Objection 2. According to some, knowledge and active power are not in the same ratio; for an active power flows from the very nature of the thing, inasmuch as action is considered to come forth from the agent; but knowledge is not always possessed by the very essence or form of the knower, since it may be had by assimilation of the knower to the thing known by the aid of received species. But this reason seems not to suffice, because even as we may understand by a likeness obtained from another, so also may we act by a form obtained from another, as water or iron heats, by heat borrowed from fire. Hence there would be no reason why the soul of Christ, as it can know all things by the similitudes of all things impressed upon it by God, cannot do these things by the same similitudes.
It has, therefore, to be further considered that what is received in the lower nature from the higher is possessed in an inferior manner; for heat is not received by water in the perfection and strength it had in fire. Therefore, since the soul of Christ is of an inferior nature to the Divine Nature, the similitudes of things are not received in the soul of Christ in the perfection and strength they had in the Divine Nature. And hence it is that the knowledge of Christ's soul is inferior to Divine knowledge as regards the manner of knowing, for God knows (things) more perfectly than the soul of Christ; and also as regards the number of things known, since the soul of Christ does not know all that God can do, and these God knows by the knowledge of simple intelligence; although it knows all things present, past, and future, which God knows by the knowledge of vision. So, too, the similitudes of things infused into Christ's soul do not equal the Divine power in acting, i.e. so as to do all that God can do, or to do in the same manner as God does, Who acts with an infinite might whereof the creature is not capable. Now there is no thing, to know which in some way an infinite power is needed, although a certain kind of knowledge belongs to an infinite power; yet there are things which can be done only by an infinite power, as creation and the like, as is plain from what has been said in I, 45. Hence Christ's soul which, being a creature, is finite in might, can know, indeed, all things, but not in every way; yet it cannot do all things, which pertains to the nature of omnipotence; and, amongst other things, it is clear it cannot create itself.
Reply to Objection 3. Christ's soul has practical and speculative knowledge; yet it is not necessary that it should have practical knowledge of those things of which it has speculative knowledge. Because for speculative knowledge a mere conformity or assimilation of the knower to the thing known suffices; whereas for practical knowledge it is required that the forms of the things in the intellect should be operative. Now to have a form and to impress this form upon something else is more than merely to have the form; as to be lightsome and to enlighten is more than merely to be lightsome. Hence the soul of Christ has a speculative knowledge of creation (for it knows the mode of God's creation), but it has no practical knowledge of this mode, since it has no knowledge operative of creation.
Source: Summa Theologica (New Advent)