19 Thus the progressive revelation contained in our Lord's reply is at one with the progressive statement of truth in the Church's confession of faith. Neither of them divides the nature, and both declare the birth. For the next words of Christ are, For the Father loves the Son, and shows Him all things that Himself does; and He will show Him greater works than these, that you may marvel. For as the Father raises up the dead, and quickens them, even so the Son quickens whom He will.
Can there be any other purpose in this revelation of the manner in which God works, except that of inculcating the true birth; the faith in a subsisting Son born from the subsisting God, His Father? The only other explanation is that God the Only-begotten was so ignorant that He needed the instruction conveyed in this showing; but the reckless blasphemy of the suggestion makes this alternative impossible. For He, knowing, as He does, everything that He is taught, has no need of the teaching.
And accordingly, after the words, The Father loves the Son, and shows Him all things that Himself does, we are next informed that all this showing is for our instruction in the faith; that the Father and the Son may have their equal share in our confession, and we be saved, by this statement that the Father shows all that He does to the Son, from the delusion that the Son's knowledge is imperfect. With this object He goes on to say, And He will show Him greater works than these, that you may marvel.
For as the Father raises up the dead and quickens them, even so the Son quickens whom He will. We see that the Son has full knowledge of the future works which the Father will show Him hereafter. He knows that He will be shown how, after His Father's example, He is to give life to the dead. For He says that the Father will show to the Son things at which they shall marvel; and at once proceeds to tell them what these things are; For as the Father raises up the dead and quickens them, even so the Son quickens whom He will.
The power is equal because the nature is one and the same. The showing of the works is an aid, not to ignorance in Him, but to faith in us. It conveys to the Son no knowledge of things unknown, but it imparts to us the confidence to proclaim His birth, by assuring us that the Father has shown to Him all the works that He Himself can do. The terms used in this Divine discourse have been chosen with the utmost deliberation, lest any vagueness of language should suggest a difference of nature between the Two.
Christ says that the Father's works were shown Him, instead of saying that, to enable Him to perform them, a mighty nature was given Him. Hereby He wishes to reveal to us that this showing was a substantive part of the process of His birth, since, simultaneously with that birth, there was imparted to Him by the Father's love a knowledge of the works which the Father willed that He should do. And again, to save us from being led, by this declaration of the showing, to suppose that the Son's nature is ignorant and therefore different from the Father's, He makes it clear that He already knows the things that are to be shown Him.
So far, indeed, is He from needing the authority of precedent to enable Him to act, that He is to give life to whom He will. To will implies a free nature, subsisting with power to choose in the blissful exercise of omnipotence.
Source: On the Trinity (New Advent)