Translated by Ch. Browne and J. Swallow.
I. This then is what might be said to cut short our opponents' readiness to argue and their hastiness with its consequent insecurity in all matters, but above all in those discussions which relate to God. But since to rebuke others is a matter of no difficulty whatever, but a very easy thing, which any one who likes can do; whereas to substitute one's own belief for theirs is the part of a pious and intelligent man; let us, relying on the Holy Ghost, Who among them is dishonoured, but among us is adored, bring forth to the light our own conceptions about the Godhead, whatever these may be, like some noble and timely birth. Not that I have at other times been silent; for on this subject alone I am full of youthful strength and daring; but the fact is that under present circumstances I am even more bold to declare the truth, that I may not (to use the words of Scripture) by drawing back fall into the condemnation of being displeasing to God.  And since every discourse is of a twofold nature, the one part establishing one's own, and the other overthrowing one's opponents' position; let us first of all state our own position, and then try to controvert that of our opponents;—and both as briefly as possible, so that our arguments may be taken in at a glance (like those of the elementary treatises which they have devised to deceive simple or foolish persons), and that our thoughts may not be scattered by reason of the length of the discourse, like water which is not contained in a channel, but flows to waste over the open land.
II. The three most ancient opinions concerning God are Anarchia, Polyarchia, and Monarchia. The first two are the sport of the children of Hellas, and may they continue to be so. For Anarchy is a thing without order; and the Rule of Many is factious, and thus anarchical, and thus disorderly. For both these tend to the same thing, namely disorder; and this to dissolution, for disorder is the first step to dissolution.
But Monarchy is that which we hold in honour. It is, however, a Monarchy that is not limited to one Person, for it is possible for Unity if at variance with itself to come into a condition of plurality;  but one which is made of an equality of Nature and a Union of mind, and an identity of motion, and a convergence of its elements to unity—a thing which is impossible to the created nature—so that though numerically distinct there is no severance of Essence. Therefore Unity  having from all eternity arrived by motion at Duality, found its rest in Trinity. This is what we mean by Father and Son and Holy Ghost. The Father is the Begetter and the Emitter;  without passion of course, and without reference to time, and not in a corporeal manner. The Son is the Begotten, and the Holy Ghost the Emission; for I know not how this could be expressed in terms altogether excluding visible things. For we shall not venture to speak of "an overflow of goodness," as one of the Greek Philosophers dared to say, as if it were a bowl overflowing, and this in plain words in his Discourse on the First and Second Causes.  Let us not ever look on this Generation as involuntary, like some natural overflow, hard to be retained, and by no means befitting our conception of Deity. Therefore let us confine ourselves within our limits, and speak of the Unbegotten and the Begotten and That which proceeds from the Father, as somewhere God the Word Himself saith.
 Heb. ii. 4; x. 38.
 Billius and others here read Authority, which is not supported by the best mss., or by the context.
 Elias explains this to mean that of old men knew only One Person in the Godhead: and until the Incarnation this knowledge was sufficient; but from that time forward they acknowledged a Second Person, and through Him a Third also, the Holy Ghost. But this explanation falls far short of Gregory's meaning, which certainly is that the movement of self-consciousness in God from all Eternity made the Generation of the Son, and the Procession of the Holy Ghost, a necessity. All is objective in God. cf. Petav. de Deo, II., viii., 16; also, Greg. Naz., Or. xxiii. 5.
 proboleus-probole was a term used by the Gnostics to describe the Emanations by which the distance between the Finite and the Infinite was according to them bridged over; and on this account it fell under suspicion, and was rejected by both Arius and Athanasius. Tertullian used it with an explanation which is satisfactory as regards the probole of the Son; but when he comes to apply it to the Procession of the Holy Ghost he uses an illustration which is in almost the very words rejected by Gregory (c. Prax., 7, 8. See Swete, p. 56). Origen did not admit it. Later when this danger was past, the word came into use again as the equivalent of ekporeusis, at first with reserve and explanations in the text, but later on as an accepted term. See Swete ,"On The Doctrine Of The Holy Spirit," p. 36.
 The expression is from Plato.
Reference address : https://www.elpenor.org/gregory-nazianzen/third-theological.asp