¹ What we reserved yesterday for your charity regarding the divinity of the Holy Spirit, we may now, if you permit, fittingly and appropriately hear with silence and attentiveness. When we declare the distinct person of the Holy Spirit and confess the Father as unbegotten and the Son as the only-begotten, you ask me whether the Holy Spirit should be confessed as unbegotten, begotten, or something else. The Holy Scriptures speak of the power and divinity of the Holy Spirit, but they do not state whether He is begotten or unbegotten.

² See the darkness that unbelief brings upon itself: you refuse to know what God did not wish to be ignored, and yet you desire to know what He did not command to be investigated. Scripture does not say the Spirit is begotten, lest you mistake Him for the Son; nor does it say He is unbegotten, lest you think Him the Father. Rather, to distinguish His essence, Scripture testifies that He proceeds from the Father, as we read: “The Advocate, the Spirit of truth, who proceeds from the Father”.

³ Given this, recognize that the Holy Spirit possesses His own distinct personhood. The difference in name proves that, besides the two, there is a third; while the unity of majesty shows that His procession from God does not place Him third in rank or degree. For the One who proceeds from the innermost being of God is not a creature of God but is revealed to be of God’s very substance.

⁴ Do not probe into how God is, when it is evident that He is God. Here, reason is hidden, but the truth is not. Why ask how the Spirit is a companion and equal of the King, when it is clear that He shares the King’s honour and nature? To inquire about the name is superfluous when there is no doubt about His majesty. Therefore, because the Holy Spirit proceeds from both the Father and the Son, it is written: “Anyone who does not have the Spirit of Christ does not belong to Him”, and elsewhere: “He breathed on them and said, ‘Receive the Holy Spirit’”.

⁵ You ask whether the Holy Spirit is unbegotten or begotten. The sacred Scriptures have sung nothing of this, and it is blasphemous to break into the divine silence. What God did not deem necessary to reveal in His Scriptures, He did not wish you to inquire about or to know through needless curiosity. Is the glory or the substance of the Holy Spirit dependent on whether He is proved to be unbegotten or begotten? Surely not. For the Son suffers no diminishment by not being called unbegotten, nor does the Father lose anything by not being described as begotten. In such matters, the distinction lies in the terms of personal designation, not in any difference of power or majesty. “Begotten” and “unbegotten” indicate a difference of person, not of nature.

⁶ Regarding the Holy Spirit, our Lord and Saviour, as He was about to ascend into heaven, spoke to His apostles in this way: “When the Advocate comes, whom I will send to you from the Father—the Spirit of truth who proceeds from the Father—He will testify about me”. And again, He said: “He will teach you all things”.

⁷ What does this mean, beloved? Why did the Saviour say that He would send the Holy Spirit to teach the disciples? Had He not already taught His apostles? Or should we consider Christ’s teaching incomplete? Certainly not! Rather, because your faith is in the Father, the Son, and the Holy Spirit, the Saviour wished, by sending the Holy Spirit, to reveal this truth: that the churches would be built by the will of God the Father, redeemed by the passion of the Son, and strengthened by the teaching of the Holy Spirit.

⁸ How can this be made clearer? How else, except by recognizing that for our redemption: God the Father sent His Son; the Son saved us by His passion; and the Holy Spirit inspired faith in us. Thus, the salvation of the churches is the work of the entire divine Trinity. For the Father, in His mercy, did not wish the human race to perish; the Son delivered us from destruction; and the Holy Spirit leads us into the heavenly kingdom.

⁹ Thus, believe in the Holy Spirit in such a way that you do not think He is the Father or the Son, but rather the Spirit of the Father and the Son. Yet, this entire Trinity is one God. There is no dissimilarity or division within it. For if the spirit within a human being is the greater part of that person, how could the Spirit of God be considered lesser? Therefore, the Holy Spirit is neither the Father nor the Son, but the Spirit of both the Father and the Son.

¹⁰ That the Holy Spirit is the Spirit of the Father, our Lord and Saviour Himself declared when He said: “The Spirit who proceeds from the Father”. And that the same Holy Spirit is also the Spirit of the Son, the Apostle teaches, saying: “Anyone who does not have the Spirit of Christ does not belong to Him”.

¹¹ Thus, the Lord, after His resurrection, said to His disciples in the Gospel: “Go, therefore, and make disciples of all nations, baptizing them in the name of the Father and of the Son and of the Holy Spirit”. He says “in the name,” not “in the names,” indicating the unity of the divine essence. Therefore, the Father is God, the Son is God, and the Holy Spirit is God—not three gods, but one God. The three persons are distinguished by their identities, but divinity unites them. The Trinity knows nothing of greater or lesser, and divinity knows no inequality, for whoever is God cannot be anything but perfect. Thus, whoever does not believe in the name of the Holy Spirit gains nothing by confessing the Father and the Son.

¹² Therefore, the Holy Spirit must be believed in with the same faith and venerated with equal reverence. When you say: “Father, Son, and Holy Spirit,” you express the persons; when you say: “God,” you declare the substance. We say “Father, Son, and Holy Spirit” so that you do not think you ought to believe in only one person. Likewise, we say “one God” so that you do not imagine there are three natures. Thus, in these three persons, there can be number but not hierarchy. For although the Trinity allows for distinction, equality knows no rank. Indeed, in the Trinity, there is nothing lesser or greater, because if anything in God were said to be lesser, divinity itself would be accused of imperfection. Therefore, whoever claims that the Holy Spirit is lesser than the Father or the Son not only insults the one they consider inferior but also dishonours the one they regard as superior. For since the entire Trinity shares one equality and majesty, any affront directed at one person is felt by the whole Trinity equally.

¹³ Dearest brothers and sisters, we who have been granted the grace to be temples of the Holy Spirit must, with the help of the same Spirit, prepare a dwelling place fit for Him—one in which He will delight to come and make His home. Let the radiance of a pure heart invite Him; let chaste modesty, adorned with the blush of roses, draw Him in; let unstained virginity, resembling the whiteness and fragrance of lilies, attract Him. Let kind charity receive Him, generous compassion welcome Him, lofty humility embrace Him, cheerful mercy gladden Him, and sincere simplicity accompany Him.

¹⁴ May the eternal Guest, the Giver of eternity, find nothing of the filth of the old self, nothing of the frailty destined for decay. Let the shameless indulgence of lust be driven out, along with a guilty conscience, sorrowful fear, staggering drunkenness, and desire—more hideous than any horror—so that, when these vices are absent from you, the brilliance of purity, as the forerunner of virtue, may open the way and enclose the Holy Spirit within the home prepared for His dwelling.

¹⁵ We offer this exhortation, dearest ones, so that, as much as we are able, we may strive with all our strength, aided by God’s grace, to ensure that neither greed displeases Him in us, nor faithlessness makes us weak, nor lust defiles us. Rather, having been thoroughly corrected and made pure, may we be found worthy to become the dwelling place of God.

¹⁶ And may the Holy Spirit, who is recorded to have descended upon the apostles today, deign to dwell in us always—He to whom belong honour and glory with the Father and the Son, forever and ever. Amen.