The Spirit is sent to all, and passes not from place to place, for He is not limited either by time or space. He goes forth from the Son, as the Son from the Father, in Whom He ever abides: and also comes to us when we receive. He comes also after the same manner as the Father Himself, from Whom He can by no means be separated.
116. The Spirit, also, is indeed said to be sent, but the Seraph to one, the Spirit to all. The Seraph is sent to minister, the Spirit works a mystery. The Seraph performs what is commanded, the Spirit divides as He wills. The Seraph passes from place to place, for he does not fill all things, but is himself filled by the Spirit. The Seraph comes down with a certain mode of passage according to his nature, but we cannot think this of the Spirit, of Whom the Son of God says: “When the Paraclete shall come, even the Spirit of Truth, Whom I send unto you, Who proceeds from the Father.”
117. For if the Spirit proceeds from a place and passes to a place, both the Father Himself will be found in a place, and the Son likewise. If He goes forth from a place, Whom the Father or the Son sends, certainly the Spirit passing from a place, and making progress, seems to leave, according to those impious interpretations, both the Father and the Son like some material body.
118. I am saying this with reference to those who say that the Spirit comes down by movement. But neither the Father, Who is above all not only of corporeal nature, but also of the invisible creation, is circumscribed in any place; nor is the Son, Who, as the Worker of all creation, is above every creature, enclosed by the places or times of His own works; nor is the Spirit of Truth as being the Spirit of God, circumscribed by any corporeal limits, Who since He is incorporeal is far above the whole rational creation through the ineffable fullness of His Godhead, having over all things the power of breathing where He wills, and of inspiring as He wills.
119. The Spirit is not, then, sent as it were from a place, nor does He proceed as from a place, when He proceeds from the Son, as the Son Himself, when He says, “I came forth from the Father, and have come into the world,” destroys all fancies, which can be reckoned as from place to place. In like manner, also, when we read that God is within or without, we certainly do not either enclose God within anybody or separate Him from anybody, but weighing these things in a deep and ineffable estimation, we comprehend the hiddenness of the divine nature.
120. Lastly, Wisdom so says that she came forth from the mouth of the Most High, as not to be external to the Father, but with the Father; for “the Word was with God;” and not only with God but also in God; for He says: “I am in the Father and the Father is in Me.” But neither when He goes forth from the Father does He retire from a place, nor is He separated as a body from a body; nor when He is in the Father is He as if a body enclosed as it were in a body. The Holy Spirit also, when He proceeds from the Father and the Son, is not separated from the Father nor separated from the Son. For how could He be separated from the Father Who is the Spirit of His mouth? Which is certainly both a proof of His eternity, and expresses the Unity of this Godhead.
121. He exists then, and abides always, Who is the Spirit of His mouth, but He seems to come down when we receive Him, that He may dwell in us, that we may not be alien from His grace. To us He seems to come down, not that He does come down, but that our mind ascends to Him. Of which we would speak more fully did we not remember that in the former treatise there was set forth that the Father said: “Let us go down and confound their language,” and that the Son said: “He that loves Me will keep My saying, and My Father will love him, and We will come to Him and make Our abode with Him.”
122. The Spirit, then, so comes as does the Father, for where the Father is there is also the Son, and where the Son is there is the Holy Spirit. The Holy Spirit, therefore, is not to be supposed to come separately. But He comes not from place to place, but from the disposition of the order to the safety of redemption, from the grace of giving life to that of sanctification, to translate us from earth to heaven, from wretchedness to glory, from slavery to a kingdom.
123. The Spirit comes, then, as the Father comes. For the Son said, “I and the Father will come, and will make Our abode with Him.” Does the Father come in a bodily fashion? Thus, then, comes the Spirit in Whom, when He comes, is the full presence of the Father and the Son.
124. But who can separate the Spirit from the Father and the Son, since we cannot even name the Father and the Son without the Spirit? “For no one says Lord Jesus, except in the Holy Spirit?” If, then, we cannot call Jesus Lord except in the Holy Spirit, we certainly cannot proclaim Him without the Spirit. But if the Angels also proclaim Jesus to be Lord, Whom no one can proclaim except in the Spirit, then in them also the office of the Holy Spirit operates.
125. We have proved, then, that the presence and the grace of the Father, the Son, and the Holy Spirit are one, which is so heavenly and divine that the Son gives thanks therefore to the Father, saying, “I give thanks to You, O Father, Lord of heaven and earth, because You have hidden these things from the wise and prudent, and hast revealed them unto babes.”
Source: On the Holy Spirit (New Advent)