Gregory of Nazianzus on the divinity of the Holy Spirit and his procession within the Trinity.
V
Chapter 6
1Or rather, let me reason with you about Him from a somewhat earlier point, for we have already discussed the Trinity. The Sadducees altogether denied the existence of the Holy Spirit, just as they did that of Angels and the Resurrection; rejecting, I know not upon what ground, the important testimonies concerning Him in the Old Testament. And of the Greeks those who are more inclined to speak of God, and who approach nearest to us, have formed some conception of Him, as it seems to me, though they have differed as to His Name, and have addressed Him as the Mind of the World, or the External Mind, and the like. But of the wise men amongst ourselves, some have conceived of him as an Activity, some as a Creature, some as God; and some have been uncertain which to call Him, out of reverence for Scripture, they say, as though it did not make the matter clear either way. And therefore they neither worship Him nor treat Him with dishonour, but take up a neutral position, or rather a very miserable one, with respect to Him. And of those who consider Him to be God, some are orthodox in mind only, while others venture to be so with the lips also. And I have heard of some who are even more clever, and measure Deity; and these agree with us that there are Three Conceptions; but they have separated these from one another so completely as to make one of them infinite both in essence and power, and the second in power but not in essence, and the third circumscribed in both; thus imitating in another way those who call them the Creator, the Co-operator, and the Minister, and consider that the same order and dignity which belongs to these names is also a sequence in the facts.