"Now this God is glorified by His Word who is His Son continually, and by the Holy Spirit who is the Wisdom of the Father of all: and the powers of these, (namely) of the Word and Wisdom, which are called Cherubim and Seraphim, with unceasing voices glorify God; and every created thing that is in the heavens offers glory to God the Father of all. He by His Word has created the whole world, and in the world are the angels;" etc.
The liturgical ring of this passage is unmistakable. We saw that Justin spoke of Eucharistic praise as being offered to the Father "through the name of the Son and the Holy Spirit." But this. hardly prepares us for such a passage as we have just read. Two interesting parallels, however, may prove suggestive. The first is from the Eucharistic Prayer of Bishop Serapion (c. A.D.350):
"May the Lord Jesus speak in us, and (the) Holy Spirit, and hymn thee through us. For thou art far above all rule and authority and power and dominion, and every name that is named, not only in this world but also in that which is to come. Beside thee stand thousand thousands and myriad myriads of angels, archangels, thrones, dominions, principalities, powers: beside thee stand the two most honorable six-winged Seraphim, with two wings covering," etc., leading up to the Ter Sanctus 
This Prayer comes to us from Egypt. When we look at the Liturgy of Alexandria, known as that of St Mark, we find that the reference to the praise offered to the Father by the Son and the Spirit is absent. And in the place of "the two most honorable Seraphim" we read: "the two most honorable living creatures (Hab. iii.2, LXX), the many-eyed Cherubim, and the six winged Seraphim."  In the other Greek Liturgies "the two living creatures" are not found, but Cherubim and Seraphim remain; and we in the West are familiar with this combination in the words of the Te Deum: "Tibi Cherubim et Seraphim incessabili voce proclamant: Sanctus, sanctus, sanctus," etc. 
The second parallel is not less remarkable. It comes from the Eucharistic Preface of the so-called Clementine Liturgy contained in the Apostolic Constitutions (viii.12). But it does not appear in the ordinary texts. Mr C. H. Turner has recently called attention to a MS. in the Vatican (Vat. Gr.1506), as offering a more original text of this work and presenting Arian features no longer to be found in the current recension. This early text contains the following words towards the close of the Preface:
"Thee every incorporeal and holy order (of beings) worshippeth; [thee the Paraclete worshippeth] and, before all, thy holy Servant Jesus the Christ, our Lord and God and thy angel and captain of the host and eternal and unending high priest: thee the well-ordered hosts of angels and archangels worship," etc. 
When now we look back to the passage in the Demonstration, with its reference to Cherubim and Seraphim who "with unceasing voices" glorify God, we feel that there is matter here which deserves the attention of students of the earliest forms of the Liturgy.
But a yet earlier witness must be called before we leave this passage. There are several places in the Demonstration which suggest that Irenæus was acquainted with the splendid vision of the Ascension of Isaiah, a Christian apocryphal writing which probably belongs to the first half of the second century. A brief outline of that vision must be given here. 
Isaiah is taken (c.7) by an angel, whose name he may not know, because he is to return to his mortal body, first up into the firmament, where he finds perpetual warfare between Satanic powers. Next he ascends into the first heaven, where he sees a throne with angels on either side; they chant a hymn of praise, which he learns is addressed to the Glory of the seventh heaven and to His Beloved. In the second heaven he finds also a throne with angels, but more glorious; he would fain fall down and worship, but is not permitted. In the third heaven he finds the like; there is there no mention of the deeds of the vain world from which he has come, but he is assured that nothing escapes observation. In the fourth heaven he again sees angels on either side of a throne, the glory of those on the right being, as before, greater than of those on the left; and all are more glorious than those below. The same in yet greater degree is true of the fifth heaven. But in the sixth heaven (c.8) there is no throne, and no left hand, but all are alike in splendor: it is in close connection with the seventh heaven, and its glory makes the glory of the five heavens below seem but darkness. At length he comes (c.9) to the seventh heaven, where his entry is challenged, but permitted. Here he sees the just clothed in their heavenly robes, but not yet having received their thrones and crowns. These they cannot have until the descent and the return of the Beloved has been accomplished. He is shown also the books which contain the transactions of the world below, and learns that all is known in the seventh heaven. He beholds the Lord of Glory, and is bidden to worship Him. He then beholds a second most glorious one, like unto Him, and again is bidden to worship; and then again a third, who is the angel of the Holy Sprit, the inspirer of the prophets. These two latter worship the ineffable Glory; and the chant of praise (c.10) sounds up from the sixth heaven. Then the voce of the Most High is heard speaking to the Lord the Son, bidding Him descend through the heavens to the firmament, and to the world, and even to the angel of the infernal regions; He is to assimilate Himself to those who dwell in each region in turn, so that He may not be recognized as He passes down. He will ascend at length with glory and worship from all. The prophet now beholds the descent of the Beloved. In the sixth heaven there is no change of His appearance, and the angels glorify Him. But in the fifth He is changed, and not recognized, and so in each of the lower heavens, down to the firmament, where He passes through the strife that rages there, still unrecognized. At this point the angel calls the prophet's special attention to what follows (c.11).
Here follows a description of the Birth from a Virgin, and a notice of the life, death, and resurrection of the Lord, and the sending forth of the Twelve (11^2.23).
Then the prophet beholds the ascent through the firmament and the six heavens: the Lord is recognized and glorified as He ascends: at length He reaches the seventh heaven, and takes His seat on the right hand of the great Glory; and the angel of the Holy Spirit sits on the left hand. The prophet is then sent back to his mortal clothing. On his return he warns Hezekiah that these things will come to pass, but that they may not be communicated to the people of Israel.
Now it is to be observed that in c.9 of the Demonstration Irenæus gives us an account of the Seven Heavens; in c.10 he speaks of God as being glorified by His Word and by the Holy Spirit; and in c.84 he says that the Lord in His descent was not recognized by any created beings, and he thus explains the dialogue with the heavenly powers in Ps. xxiv: "Lift up your gates, ye rulers . . . Who is the King of Glory?" and so forth. We cannot therefore reasonably doubt that Irenæus was acquainted with the vision in the Ascension of Isaiah.
The words which immediately concern us here are at the end of the ninth chapter of that book: "I saw that my Lord worshipped, and the angel of the Spirit, and that both of them together glorified God. And immediately all the saints approached and worshipped: and all the saints and angels approached and worshipped, and all the angels glorified."
We see then that Irenæus by no means stands alone in his statement that the God and Father of all is glorified by the Son and by the Holy Spirit. Strange as the conception is to us it was not strange to the religious mind of the second Christian century. It would appear to have found place in an early form of the Liturgy, and to have been retained by the Arian compiler of the so-called Clementine Liturgy of the Apostolic Constitutions: for the Arians not infrequently could claim to be conservative in points of detail. Possibly we may even trace it, in a form modified into harmony with a later orthodoxy, in the Liturgy of Serapion; but it is cast out altogether in the Greek Liturgies of the subsequent period, and by the orthodox reviser of the Apostolic Constitutions.
As the Demonstration starts from the Rule of Faith -- the "three points" of the Creed -- it necessarily has something to say of the relation of the Spirit to the Father and the Son: but at once we feel that Irenæus finds difficulty in drawing a clear distinction between the functions of the Word and the Spirit. In c.5 he says: God is rational (logikos); therefore He creates by the Word (logos): God is Spirit; therefore He orders all by the Spirit. Here Ps. xxxiii.6 comes to his aid: "By the word of the Lord were the heavens established, and by his spirit all their power." Then, having identified the Word with the Son, he identifies the Spirit with the Wisdom of God. After this he takes refuge in St Paul: "One God, the Father," etc. But the passage must be given in full.
"Since God is rational, therefore by (the) Word [or Reason] He created the things that were made; and God is Spirit, and by (the) Spirit He adorned all things: as also the prophet says: By the word of the Lord were the heavens established, and by his spirit all their power. Since then the Word establishes, that is to say, gives body and grants the reality of being, and the Spirit gives order and form to the diversity of the powers; rightly and fittingly is the Word called the Son, and the Spirit the Wisdom of God. Well also does Paul His apostle say: One God, the Father, who is over all and through all and in us all. For over all is the Father; and through all is the Son, for by means of Him all things were made by the Father; and in us all is the Spirit, who cries Abba Father, and fashions man into the likeness of God.  Now the Spirit shows forth the Word," etc. 
Here we have moved a long way from Justin, who does not connect the Holy Spirit with the work of creation, nor quote Ps. xxxiii.6; and who expressly tells us more than once that it is the Son who is called Wisdom by Solomon (Dial.62 and 126). It is to other writings of Irenæus himself that we must look for illustration of these words of the Demonstration.
We begin with Isa. xxxiv.1 ff., a passage which contains so many illustrations of the language of the Demonstration that we must quote it at some length. The translation is made from a comparison of the Latin and Armenian versions: where it does not accord with the Latin, it is to be assumed that the Armenian is followed.
(1) So then according to His greatness it is not possible to know God; for it is impossible that the Father should be measured. But according to His love -- for love it is which leads us to God through His Word -- as we obey Him we ever learn that He is so great a God, and that it is He who by Himself created and made and adorned and contains all things. Now in all things are both we and this world of ours:  therefore we also were made together with those things that are contained by Him. And it is this concerning which the Scripture says: And the Lord God formed man, dust of the earth; and breathed in his face the breath of life (Gen. ii.7). Angels therefore made us not, nor formed us: for neither could angels make the image of God, nor could any other except the true God, nor any power standing remote from the Father of all. For of none of these was God in need to make whatsoever He of Himself had foreordained should be made: as though He Himself had not His own Hands. For ever with Him is the Word and Wisdom -- the Son and the Spirit -- through whom and in whom freely and of His own power He made all things; unto whom also the Father speaks,  saying: Let us make man after our image and likeness: taking from Himself the substance of the things created, and the pattern of those made, and the form of those adorned.
(2) "Well then spake the Scripture which says: First of all believe that there is one God, who created and fashioned all things, and made all things to be from that which was not; and containeth all things, and alone is uncontained.  Well also in the prophets says the Angel:  Hath not one God created its? Is there not one Father of us all (Mal. ii.10)? And agreeably with this the Apostle says: One God and Father, above all and through all and in us all (Eph. iv.6). In like manner also the Lord says: All things have been delivered unto me by my Father (Matt. xi.27); plainly by Him who made all things: for He gave Him not the things of another, but His own." 
"And in all things there is nothing excepted. And for this cause He is Judge of quick and dead; having the key of David, opening and none shall shut, and He shall shut and none shall open (Rev. iii.7). For none other was able, neither in heaven nor on earth nor beneath the earth to open the Father's book, nor to look thereon, save the Lamb that was slain and redeemed us by his blood Rev. v.2); having received all power from Him, who by the Word made and by Wisdom adorned all things, when the Word was made flesh (John i.14) that as in heaven He had the preeminence,  because He was the Word of God, so also on earth He should have the preeminence, because He was a just man,  who did no sin, neither was guile found in his mouth (I Pet. ii.22); and that He should have the preeminence also over those who are beneath the earth, being made the first-begotten from the dead (Rev. i.5): and that all things should behold, as we have said, their King: and that the Father's light should come upon the flesh of our Lord, and from His flesh sparkling and flashing back should come to us, and so man should be drawn and caught into the incorruption of the Father's light.
(3) Now that the Word, that is, the Son, was always with the Father,  we have shown by many proofs. And that Wisdom, which is the Spirit, was with Him before all creation, He says by Solomon, thus: God by wisdom founded the earth, and he prepared the heaven by understanding: by His knowledge the depths were broken up, and the clouds dropped down the dew (Prov. iii.19 f.). And again: The Lord created me (in Arm.) the beginning of his ways, for his works," etc. (Prov. viii.22-25).
(4) "There is therefore one God, who by the Word and Wisdom made and fashioned all things . . ."
So the great passage runs on: later portions of it describe the work of the Holy Spirit among men. The footnotes have shown how much of it is repeated in almost the same words in the Demonstration, apart from the particular section which we have called it in to illustrate. To that section we must return; for we are now concerned with the Spirit's work in connection with Creation.
First we must deal with the quotation, By the word of the Lord were the heavens established, and by his spirit all their power. This is quoted more correctly -- "by the spirit (or breath') of his mouth" -- in I, xv and also in III, viii.3.
In the latter place he makes no comment; but in
Next we note the expression "by the Spirit He adorned them." This word "adorned" (Lat. adornavit) recurs several times in the passage we have quoted from Bk. IV: "created and made and adorned and contains all things;" "the form of the things adorned," "who by the Word made and by Wisdom adorned all things." The Armenian word is the same throughout, and probably represents the Greek ekosmesen and ton kekosmemenon.  At the end of the passage we have a similar phrase: "who by the Word and Wisdom made and fashioned all things (Lat. adaptavit)." 
The passage in the Demonstration goes on to say that "rightly and fittingly is the Word called the Son, and the Spirit the Wisdom of God." The proof texts for this latter statement are not given: but we have had them in the long passage from the fourth book Against Heresies. For the purpose of asserting the part of the Holy Spirit in Creation, Irenæus has boldly taken over the texts which speak of Wisdom in this connection -- texts which Justin before him and Origen  after him would have referred to the Son.
This equivalence in creative function of the Son and the Spirit, as the Word and the Wisdom of God, is strangely expressed in Bks. IV and V, by calling them the Hands of God. In IV, pref.3 we read: "Man is a mingling of soul and flesh,  fashioned after the likeness of God and formed (plasmatus) by His Hands, that is, by the Son and the Spirit, to whom also He said: Let us make man." The conception is developed in IV, xiv.1: "The Father had no need of angels to make the world and to form man for whose sake the world was made; nor again was He in want of ministration for the making of created things and the dispensation of the work that concerned man but He had abundant and unbounded ministration; because there ministers unto Him His own Offspring for all purposes, and His own Hands,  that is, the Son and the Spirit, the Word and Wisdom to whom all the angels render service and are in subjection." The next occurrence of the metaphor is in the great passage we have quoted above (IV, xxxiv.1, "as though He had not His own Hands"), where he practically repeats what he has said before.
Then in V, i.3 we have: "For never at any time has Adam escaped the Hands of God, to whom the Father spake, saying: Let us make man after our image and likeness. And for this cause in the end (of the times), not of the will of flesh nor of the will of man (John i.13), but of the good pleasure of the Father, His Hands made the Living Man, that Adam might become after the image and likeness of God." Here we see the conception carried on from the Creation to the Incarnation.
In V, v.1, speaking of Enoch and Elijah, he says: "By those Hands by which they were formed (eplasthesan) at the beginning they were translated and taken up: for in Adam the Hands of God were habituated to order and hold and carry their own formation (plasma), and to bear it and set it where they themselves would." He goes on to say that "the Hand of God was present "with the Three Children in the Furnace -- namely "the Son of God."
Then in V, vi.1 the continual molding of man is indicated: "God shall be glorified in His own formation (plasmate), conforming and conjoining it to His Son. For by the Hands of the Father, that is, the Son and the Spirit, man is made after the image and likeness of God -- but not part of man." He is arguing for the resurrection of the flesh, not of the soul alone.
In V, xv.2 f. our Lord's cures in the Gospels are said to show the Hand of God, which formed man at the beginning: cf. also xvi.1.
Lastly, in V, xxviii.3, he returns to the two Hands: "Wherefore in all this time (viz. the 6000 years) man, formed at the beginning by the Hands of God, that is, the Son and the Spirit, is being made after the image and likeness of God."
In the Demonstration the same thought is suggested by the phrase in c.11: "But man He formed with His own Hands;" but it is not further dwelt upon.
The identification of the Spirit with Wisdom was made after a fashion by some of the "Gnostics," but not in a way that is likely to have influenced Irenæus.  Nor do I know where else to find it at this date except in Theophilus of Antioch. But on his name we must pause for a brief digression. He seems to have written a little earlier than Irenæus, who is generally admitted to have had some acquaintance with his works.
In approaching what Theophilus of Antioch has to say concerning the Holy Spirit, it is of the first importance to bear in mind that his three books addressed to Autolycus represent a systematic attempt to convert a heathen from the worship of a plurality of Gods. A higher faith is set before him, but it is not what we today should speak of as distinctively Christian. There is no Christian theology, properly so called, propounded: the Incarnation, Passion, Resurrection of our Lord are not mentioned; the very names Christ and Jesus are absent:  the Gospels are referred to only in passing for certain moral precepts. Much of the work is directly controversial and negative: his positive arguments are concerned with the process of Creation as revealed to Moses and with prophecies of the Old Testament. In these Scriptures and in the Gospels, so far as he touches on them, he finds the inspiring activity of the Spirit of God: but Creation, not less than Inspiration, is for him a function of God's Wisdom as well as of God's Word; and, though he does not explicitly identify Wisdom with the Holy Spirit, his language certainly implies that this was his meaning.
Theophilus leads off with a general statement which is perhaps to be explained by his anxiety to keep the Unity of God in the front of his exposition. The form of God, he says, is ineffable: "if I call Him Light, I speak of His handiwork; if Word of His rule" -- for he explains later that arche means "rule" (hoti archei) as well as "beginning"; "if I call Him Mind, I speak of His understanding; if Spirit, of His breath; if Wisdom, of His offspring; if Strength, of His might; if Power, of His working; if Providence, of His goodness," and so on. 
Here we have "Word," "Spirit," "Wisdom " -- as it were Names of God: a sort of warning that, if these are hereafter mentioned as active powers, they are not to be thought of as infringing on the Unity of the Deity.
Next, in i.5, we read: "the whole creation is embraced by the Spirit of God, and the Spirit that embraces it is together with the creation embraced by the hand of God." This does not encourage us to expect a very clear definition of terms.
In i.7 we get what is more to our purpose. He is speaking of God as the Physician who can open the eyes of the soul: "God, who heals and quickens by the Word and Wisdom. For God by His Word and Wisdom made all things. For by his word were the heavens established, and by his spirit all their power. Most excellent is His Wisdom: God by wisdom founded the earth, and prepared the heavens by understanding: by (his) knowledge the depths were broken up, and the clouds dropped down the dew."
This might be Irenæus himself.  There is the same inexact quotation of Ps. xxxiii.6, with "his spirit," instead of "the spirit (or breath') of his mouth"; and the same full quotation of Prov. iii.19, 20, where the former verse only might have been expected. Moreover the next sentences of Theophilus give in summary form much which is said with great fullness by Irenæus, touching the vision of God and the resurrection of the flesh as well as of the soul.
In ii.9 Wisdom and Holy Spirit are found in close conjunction. The prophets being "spirit-bearers of holy Spirit" (pneumatophoroi pneumatos hagiou) were able to take in the Wisdom that is from Him (i. e. from God) and by this Wisdom spoke of creation and of other things, future as well as past. Wisdom is here connected with the Holy Spirit, yet not expressly identified with Him.
We go on (ii.10) to what the prophets have told us about the creation. Out of what did not exist God made all things. For God has no coeval. Though in need of nought in His existence before the ages, yet He willed to make man, by whom He might be known. So He made the world in preparation for man. And this is how He did it: "God having His own Word existent within His own heart (endiatheton), begat Him, together with His own Wisdom, uttering Him forth before all things.  This Word He used as minister for the things brought into being by Him, and through Him He made all things. This (Word) is also called Rule (arche, hoti archei), because He rules and dominates all that has been created through Him. This (Word) therefore, being Spirit of God and Rule and Wisdom and Power of the Highest, came down upon the prophets and through them spoke of the world's creation and all other things. For the prophets were not there when the world was made, but (only) the Wisdom of God which is in Him, and His holy Word who is ever present with Him. So Solomon says "When he prepared the heaven I was present with him," and so on. "And long before Solomon Moses, or rather the Word of God through him as an instrument, says: In the beginning God made the heaven and the earth." Then follows a mention of the Divine Wisdom "as foreknowing the foolish idolatries of men, and as saying In the beginning God made, that it might be understood that "in His Word God made the heaven and the earth."
It may be that Theophilus thus passes from the Word of God to the Wisdom of God, and back again, and even calls the Word both Spirit of God and Wisdom, in order to maintain the ruling conception of the Unity of the Deity. He speaks of God as begetting His own Word together with His own Wisdom -- and we remember that in an earlier place he spoke of Wisdom as the offspring (gennema) of God -- but he has not used the word "Son," though this he will have to do later. He writes so clearly when he chooses, that we are almost forced to conclude that he is withholding the fuller doctrine with intentional reserve from one who still persists in his heathen beliefs.
He now quotes (ii. ii) the whole of the first chapter of Genesis, and begins to comment on it, first noting "the exceeding greatness and riches of the Wisdom of God" displayed in it. Presently (ii.13) he says that, unlike man, God can begin His building from the roof. Therefore "In the beginning God made the heaven, that is, through the Beginning (dia tes arches) the heaven was made, as we have explained." He has already called the Word arche, though in the sense of Rule. The Spirit appears as the vivifying power in connection with the water. Then "the Command (he diataxis) of God, that is, His Word," introduces light. Then the Word of God gathers the waters "into one assembly" (eis sunagogen), a phrase which presently allegorized. 
When he comes to the fourth day, on which the luminaries were created, he offers some allegorical interpretations. Man, though not yet created, is in a way anticipated and prefigured. The sun, never waning, is a type of God in His eternal fullness: the moon with her changes is a type of man, his rebirth and resurrection. "In like manner also," he proceeds, "the three days before the luminaries were made are types of the triad -- God and His Word and His Wisdom;  and to the fourth type (what corresponds) is man, who needs the light: so that there may be God, Word, Wisdom, Man. This is why the luminaries were made on the fourth day." And he goes on to interpret the stars, bright and less bright, as the prophets and other just men; and the planets as wanderers from God.
Here for a moment we seem to have got the doctrine of the Holy Trinity, and the identification of Wisdom with the Spirit. And we have no earlier example of the use of the word Trias in this sense. But we are instantly warned off from such a view by his introduction of Man as a fourth member of the series. If he has come too near enunciating the Trinity, he certainly escapes, covering his tracks. Is it possible that these were "words to the wise"? At any rate he has said nothing that could raise in the mind of Autolycus any thought of plurality of Gods.
In ii.18 he comes on to the creation of man. First the high dignity of man is indicated in the words, Let us make man after our image and likeness. "For when God had made all things by word, and counted them all as subsidiary (parerga), the making of man He alone counted work of His own hands. Yea more, as though needing assistance, God is found saying, Let us make . . . But to none other did He say it, save to His own Word and His own Wisdom."
Here again we almost seem to be listening to Irenæus. Is it possible that it is in view of the indistinctness of this very teaching that Irenæus so often reiterates that the Word and the Wisdom are the Son and the Spirit, and that these are the Hands of God? Theophilus has almost said it himself: but he has stopped short of saying it. And in a later chapter (ii.22) he will return to the old vagueness, and tell us that it was "not the God and Father of all . . . but His Word, through whom He made all things, who, being His Power and His Wisdom, represented the Father of all," and conversed in Paradise with Adam. And he adds that the Voice Adam heard is "the Word of God, who is also His Son (huios autou): not indeed as poets and mythologers speak of sons of the gods begotten by intercourse; but as truth declares concerning the Word who is ever existent within (endiatheton) the heart of God. For before anything was made He had Him to His Counselor, as being His own mind and understanding. But when He willed to make what He had counseled, He begat this Word into outwardness (prophorikon), as first-begotten of all creation: not being Himself emptied of the Word, but having begotten the Word, and for ever conversing with His Word." He then quotes the first verses of St John's Gospel; but he does not go on to "the Word made flesh."
In all this we have much that reminds us of Irenæus, and there are yet closer parallels to be found in later chapters. We cannot but regret that we have none of those works of Theophilus which would have given us his more distinctively Christian teaching, such as Autolycus might have received had he been willing to become a catechumen. We have enough at any rate to make us feel that Irenæus was not on wholly new ground in this particular matter, even if he trod it much more firmly than his predecessor.
We now return to the Demonstration and read a passage in which Irenæus sums up a portion of his argument (c.47). "So then the Father is Lord and the Son is Lord, and the Father is God and the Son is God: for that which is begotten of God is God." This surprises us alike by its anticipation of a later formula, and by its silence in regard to the Holy Spirit. It is only at a later point after a quotation from Ps. xlv, that the Spirit is mentioned: "The Son, as being God, receives from the Father, that is, from God, the throne of the everlasting kingdom, and the oil of anointing above His fellows. The oil of anointing is the Spirit, wherewith He has been anointed." This statement is also found in III, xix.3: and in III, vi.1 we read: "Since therefore the Father is truly Lord and the Son is truly Lord, the Holy Spirit duly indicated them by the title of Lord;" and, after certain texts have been quoted: "For the Holy Spirit indicated both by the title of Lord -- Him who is anointed, even the Son, and Him who anoints, that is, the Father." 
The concern of Irenæus, as of Justin before him, is with the Father and the Son; and he writes always with the heresy of Marcion in the back of his mind. It would seem as though no question of the Deity of the Holy Spirit occurred to him. The Spirit was the Spirit of God and the Spirit of Christ. It was necessary to insist that "that which is begotten of God is God:" the Godhead of the Son required proof. But to say that "the Spirit of God" is truly God would have been to him a tautology. The thought of the Spirit as God did not as yet involve any such distinction as could seem to conflict with the Unity of the Deity.
To do justice to the teaching of Irenæus so far as it regards the relation of the Holy Spirit to the Father and the Son, it would be necessary to examine what he has to tell us of the Spirit's work in the process of man's restoration. An adequate consideration of this would correct the one-sided view which is all that we gain, from treating of the points on which his conceptions are farthest removed from those with which we ourselves are familiar. It has been necessary to consider these points with some fullness, because it is important to observe how much still remained unsettled, and how great a task still lay before the leaders of Christian thought before such definitions could be reached as should adequately guard the Catholic doctrine of the Holy Trinity. It is not possible however to do more within our present limits, and it is fortunate for us that the gap may be filled by a reference to the careful and sympathetic exposition of Dr. Swete in his valuable work on The Holy Spirit in the Ancient Church (1912, pp.89-94). "Irenæus," he tells us, "enters into the details of the Holy Spirit's work on the hearts and lives of men with a fullness which is far in advance of other Christian writers of the second century." And he sums up by saying: "On the whole, the pneumatology of Irenæus is a great advance on all earlier Christian teaching outside the Canon." With this apology for incompleteness we must pass on to the third and last point of our subject.