31 Then, finally, to express in words the whole Mystery, He raised His eyes to heaven, and said, Father, the hour has come: glorify Your Son, that Your Son may glorify You. Even as You gave Him authority over all flesh, that, whatsoever You have given Him, to them He should give eternal life. Do you call Him weak because He asks to be glorified? So be it, if He does not ask to be glorified in order that He may Himself glorify Him by Whom He is glorified. Of the receiving and giving of glory we have spoken in another book, and it would be superfluous to go over the question again.
But of this at least we are certain, that He prays for glory in order that the Father may be glorified by granting it. But perhaps He is weak in that He receives power over all flesh. And indeed the receiving of power might be a sign of weakness if He were not able to give to those whom He receives life eternal. Yet the very fact of receiving is used to prove inferiority of nature. It might, if Christ were not true God by birth as truly as is the Unbegotten. But if the receiving of power signifies neither more nor less than the Birth, by which He received all that He has, that gift does not degrade the Begotten, because it makes Him perfectly and entirely what God is.
God Unbegotten brought God Only-begotten to a perfect birth of divine blessedness: it is, then, the mystery of the Father to be the Author of the Birth, but it is no degradation to the Son to be made the perfect image of His Author by a real birth. The giving of power over all flesh, and this, in order that to all flesh might be given eternal life, postulates the Fatherhood of the Giver and the Divinity of the Receiver: for by giving is signified that the One is the Father, and in receiving the power to give eternal life, the Other remains God the Son.
All power is therefore natural and congenital to the Son of God; and though it is given, that does not separate Him from His Author, for that which is given is the property of His Author, power to bestow eternal life, to change the corruptible into the incorruptible. The Father gave all, the Son received all; as is plain from His words, All things, whatsoever the Father has, are Mine. He is not speaking here of species of created things, and processes of material change, but He unfolds to us the glory of the blessed and perfect Divinity, and teaches us that God is here manifested as the sum of His attributes, His power, His eternity, His providence, His authority; not that we should think that He possesses these as something extraneous to Himself, but that by these His qualities He Himself has been expressed in terms partly comprehensible by our sense.
The Only-begotten, therefore, taught that He had all that the Father has, and that the Holy Spirit should receive of Him: as He says, All things, whatsoever the Father has, are Mine; therefore I said, He shall take of Mine. All that the Father has are His, delivered and received: but these gifts do not degrade His divinity, since they give Him the same attributes as the Father.
Source: On the Trinity (New Advent)