I will therefore set forth in a few words what Christ teaches us in the saying before us.
By saying that another will be sent to us from God the Father, He again confirms this doctrine for the purposes of the divine economy.
For some, misunderstanding this saying, might think that the Holy Spirit, according to His words, is not from the essence of God, as it appears to certain foolish people, but is something else by nature.
The expression "another" could serve as an especially strong basis for such an opinion.
Therefore, to show clearly that He wishes this difference to be understood in no other way than as His own distinct personal or hypostatic existence, He says that the Advocate will be sent and promises to come Himself.
For the Spirit is Spirit, and not Son, just as the Son is Son, and not Father.
By this He shows that the Spirit is nothing other than what He Himself is, since He is the Father's own Spirit and is understood as His Spirit.
For this reason He is also called His mind. Thus Paul, pointing to this very thing, says, "But we have the mind of Christ" (1 Cor 2:16).
Therefore, understanding this rightly and without error, rejecting the distortion of the truth as a shameful thing, and following the words of divinely inspired Scripture, we shall say that He is nothing other than Him.
This is said with regard to natural identity, distinctly and separately. Understanding this, I think, divine Paul often joins the One and the Other and introduces Them as one and the same, I mean the Advocate and the Son.
Thus you will find him saying, "If anyone does not have the Spirit of Christ, he is none of His" (Rom 8:9).
And again immediately after this: "But if Christ is in you, the body is dead because of sin, but the Spirit is life because of righteousness" (Rom 8:10).
Do you hear how clearly he acknowledges that those who have received His Spirit have Christ? He also says elsewhere, "I think that I too have the Spirit of God" (1 Cor 7:40).
He is the same one who said to us, "If you seek proof that Christ speaks in me" (2 Cor 13:3).
He often boasts that Christ has dwelt in us who have believed through faith, although he also receives the Holy Spirit.
Let no one think that we say he abolishes the meaning of the distinction of names or persons in relation to the One and the Other.
Nor should anyone think that he does not consider the Son to be Son, but Spirit, or that he does not acknowledge the Spirit as Spirit, but considers Him Son.
This was not the aim of that saying, and we do not believe in this way. He knows the threeness of the Holy and Consubstantial Trinity.
He also teaches the distinct existence, idia hyphesthai, of each of the divine Persons signified. Yet at the same time he clearly proclaims that the Holy Trinity abides in unchangeable identity.
Otherwise, how can the Spirit be God and be called God? "Do you not know," he says, "that you are the temple of God, and that the Spirit of God dwells in you?" (1 Cor 3:16).
If we have become temples of God because the Spirit dwells in us, then how can the Spirit who causes God to dwell in us through Himself not be from God, that is, from His essence?
Therefore the Only-begotten, showing that the Spirit is not alien to His own nature, says that the Advocate will be sent to the saints from the Father.
He promises that He Himself will come and fill the place of the Father for them. Thus they will not be like certain orphans, deprived of protecting help.
Nor will they thereby be easily caught in the snares of the devil or very readily inclined to the scandals in the world.
These scandals are very numerous and come almost of necessity because of the unbridled frenzy of those who bring them about.
Thus, as an instrument and unshakable support for our souls, the Father gave the Spirit of Christ, who fulfills in us His grace, presence, and power.
Indeed, it is impossible for the human soul to accomplish anything good, restrain its passions, or escape the very great and strong snare of the devil, unless it is fenced about by the grace of the Holy Spirit.
For this reason it has Christ Himself within itself. So too the divine Psalmist, composing thanksgiving for this through the wisdom present in him, cried out to God: "O Lord, as with a shield of favor You have crowned us" (Ps 5:13).
By the shield of favor he meant nothing other than the Holy Spirit, who protects us and by unimaginable power keeps us in what is pleasing to God.
Therefore He promises that He will be present and help through the Spirit those who believe in Him, even though He will ascend into the heavens themselves after being made alive from the dead.
He will ascend "now to appear in the presence of God for us," according to Paul's word (Heb 9:24).