A quick post on Thomas Aquinas and the power of the Father in begetting the Son:
In the Summa 1.41, Thomas has a lengthy discussion about the “notional acts” in God. For Thomas, the “notions” are the five properties that make known to us the distinctions between the three Divine Persons: innascibility (ingenerateness), paternity, filiation (sonship), common spiration (common, given the filioque), and procession. So the notional acts are those internal operations in God by which the Father begets the Son and by which the Father and Son spirate the Holy Spirit.
At 1.41.5, Thomas raises the question as to whether or not these notional acts are connected with any power (potentia) in God. At first blush, it would seem that they are not, given that no active power can “belong to one person with respect to another, since the divine persons were not made.” But Thomas goes on to argue that since the notional acts exist in God there must be a “power in God with respect to these acts, since power only means principle of act.” Thus, he concludes, “we must attribute the power of generating to the Father, and the power of spiration to the Father and the Son; for the power of generation means that whereby the generator generates.”
So in some sense we can say the the Father acts with power with regard to the Son in his eternal generation. But in the next article, 1.41.6, Thomas asks what this power signifies–or where this power resides, as it were: in the personal relations or in the divine essence? Thomas answers that the power (and also the will) of the notional acts inheres in the shared essence. “Power” simply means the capacity by which an agent acts, and this capacity inheres in the essence of the agent. So it is with God. The Father begets the Son through the divine nature. The notional acts proceed from the divine essence: “The Son was not begotten from nothing but from the Father’s substance” (1.41.3).
So, for Thomas, the Father does exercise power with regard to the Son. But this power is only with reference to the Son’s eternal generation (not any kind of commanding and obeying), and it proceeds from the shared divine essence. This is all pretty granular stuff. But this is the great strength of the Scholastics: theological precision. This is tough sledding, to be sure, but it should caution us against drawing hasty conclusions about what voices from the past meant when they used terms like power, authority, and even subordination with regard to the Divine Persons.