It is time, then, that we say a few words to the best of our ability regarding the Holy Spirit, whom our Lord and Saviour in the Gospel according to John has named the Paraclete. For as it is the same God Himself, and the same Christ, so also is it the same Holy Spirit who was in the prophets and apostles, i.e., either in those who believed in God before the advent of Christ, or in those who by means of Christ have sought refuge in God. We have heard, indeed, that certain heretics have dared to say that there are two Gods and two Christs, but we have never known of the doctrine of two Holy Spirits being preached by any one.  For how could they maintain this out of Scripture, or what distinction could they lay down between Holy Spirit and Holy Spirit, if indeed any definition or description of Holy Spirit can be discovered? For although we should concede to Marcion or to Valentinus that it is possible to draw distinctions in the question of Deity, and to describe the nature of the good God as one, and that of the just God as another, what will he devise, or what will he discover, to enable him to introduce a distinction in the Holy Spirit? I consider, then, that they are able to discover nothing which may indicate a distinction of any kind whatever.
2. Now we are of opinion that every rational creature, without any distinction, receives a share of Him in the same way as of the Wisdom and of the Word of God. I observe, however, that the chief advent of the Holy Spirit is declared to men, after the ascension of Christ to heaven, rather than before His coming into the world. For, before that, it was upon the prophets alone, and upon a few individuals -- if there happened to be any among the people deserving of it -- that the gift of the Holy Spirit was conferred; but after the advent of the Saviour, it is written that the prediction of the prophet Joel was fulfilled, "In the last days it shall come to pass, and I will pour out my Spirit upon all flesh, and they shall prophesy,"  which is similar to the well-known statement, "All nations shall serve Him."  By the grace, then, of the Holy Spirit, along with numerous other results, this most glorious consequence is clearly demonstrated, that with regard to those things which were written in the prophets or in the law of Moses, it was only a few persons at that time, viz., the prophets themselves, and scarcely another individual out of the whole nation, who were able to look beyond the mere corporeal meaning and discover something greater, i.e., something spiritual, in the law or in the prophets; but now there are countless multitudes of believers who, although unable to unfold methodically and clearly the results of their spiritual understanding,  are nevertheless most firmly persuaded that neither ought circumcision to be understood literally, nor the rest of the Sabbath, nor the pouring out of the blood of an animal, nor that answers were given by God to Moses on these points. And this method of apprehension is undoubtedly suggested to the minds of all by the power of the Holy Spirit.
3. And as there are many ways of apprehending Christ, who, although He is wisdom, does not act the part or possess the power of wisdom in all men, but only in those who give themselves to the study of wisdom in Him; and who, although called a physician, does not act as one towards all, but only towards those who understand their feeble and sickly condition, and flee to His compassion that they may obtain health; so also I think is it with the Holy Spirit, in whom is contained every kind of gifts. For on some is bestowed by the Spirit the word of wisdom, on others the word of knowledge, on others faith; and so to each individual of those who are capable of receiving Him, is the Spirit Himself made to be that quality, or understood to be that which is needed by the individual who has deserved to participate.  These divisions and differences not being perceived by those who hear Him called Paraclete in the Gospel, and not duly considering in consequence of what work or act He is named the Paraclete, they have compared Him to some common spirits or other, and by this means have tried to disturb the Churches of Christ, and so excite dissensions of no small extent among brethren; whereas the Gospel shows Him to be of such power and majesty, that it says the apostles could not yet receive those things which the Saviour wished to teach them until the advent of the Holy Spirit, who, pouring Himself into their souls, might enlighten them regarding the nature and faith of the Trinity. But these persons, because of the ignorance of their understandings, are not only unable themselves logically to state the truth, but cannot even give their attention to what is advanced by us; and entertaining unworthy ideas of His divinity, have delivered themselves over to errors and deceits, being depraved by a spirit of error, rather than instructed by the teaching of the Holy Spirit, according to the declaration of the apostle, "Following the doctrine of devils, forbidding to marry, to the destruction and ruin of many, and to abstain from meats, that by an ostentatious exhibition of stricter observance they may seduce the souls of the innocent." 
4. We must therefore know that the Paraclete is the Holy Spirit, who teaches truths which cannot be uttered in words, and which are, so to speak, unutterable, and "which it is not lawful for a man to utter,"  i.e., which cannot be indicated by human language. The phrase "it is not lawful" is, we think, used by the apostle instead of "it is not possible;" as also is the case in the passage where he says, "All things are lawful for me, but all things are not expedient: all things are lawful for me; but all things edify not."  For those things which are in our power because we may have them, he says are lawful for us. But the Paraclete, who is called the Holy Spirit, is so called from His work of consolation, paraclesis being termed in Latin consolatio. For if any one has deserved to participate in the Holy Spirit by the knowledge of His ineffable mysteries, he undoubtedly obtains comfort and joy of heart. For since he comes by the teaching of the Spirit to the knowledge of the reasons of all things which happen -- how or why they occur -- his soul can in no respect be troubled, or admit any feeling of sorrow; nor is he alarmed by anything, since, clinging to the Word of God and His wisdom, he through the Holy Spirit calls Jesus Lord. And since we have made mention of the Paraclete, and have explained as we were able what sentiments ought to be entertained regarding Him; and since our Saviour also is called the Paraclete in the Epistle of John, when he says, "If any of us sin, we have a Paraclete with the Father, Jesus Christ the righteous, and He is the propitiation for our sins;"  let us consider whether this term Paraclete should happen to have one meaning when applied to the Saviour, and another when applied to the Holy Spirit. Now Paraclete, when spoken of the Saviour, seems to mean intercessor. For in Greek, Paraclete has both significations -- that of intercessor and comforter. On account, then, of the phrase which follows, when he says, "And He is the propitiation for our sins," the name Paraclete seems to be understood in the case of our Saviour as meaning intercessor; for He is said to intercede with the Father because of our sins. In the case of the Holy Spirit, the Paraclete must be understood in the sense of comforter, inasmuch as He bestows consolation upon the souls to whom He openly reveals the apprehension of spiritual knowledge.
 According to Pamphilus in his Apology, Origen, in a note on Titus 3:10, has made a statement the opposite of this. His words are: "But there are some also who say, that it was one Holy Spirit who was in the prophets, and another who was in the apostles of our Lord Jesus Christ."--Ruæus.  Joel 2:28.  Psalm 72:11.  Qui licet non omnes possint per ordinem atque ad liquidum spiritualis intelligentiæ explanare consequentiam.  Ita per singulos, qui eum capere possunt, hoc efficitur, vel hoc intelligitur ipse Spiritus, quo indiget ille, qui eum participare meruerit. Schnitzer renders, "And so, in every one who is susceptible of them, the Spirit is exactly that which the receiver chiefly needs."  1 Timothy 4:1-3.  2 Corinthians 12:4.  1 Corinthians 10:23.  1 John 2:1, 2.
 Joel 2:28.
 Psalm 72:11.
 Qui licet non omnes possint per ordinem atque ad liquidum spiritualis intelligentiæ explanare consequentiam.
 Ita per singulos, qui eum capere possunt, hoc efficitur, vel hoc intelligitur ipse Spiritus, quo indiget ille, qui eum participare meruerit. Schnitzer renders, "And so, in every one who is susceptible of them, the Spirit is exactly that which the receiver chiefly needs."
 1 Timothy 4:1-3.
 2 Corinthians 12:4.
 1 Corinthians 10:23.
 1 John 2:1, 2.