Gregory again discusses the generation of the Only-Begotten, and other different modes of generation, material and immaterial, and nobly demonstrates that the Son is the brightness of the Divine glory, and not a creature
And now let us return once more to the precise statement of Eunomius. “We believe also in the Son of God, the only begotten God, the first-born of all creation, very Son, not Ungenerate, verily begotten before the worlds.” That he transfers, then, the sense of generation to indicate creation is plain from his expressly calling Him created, when he speaks of Him as “coming into being” and “not uncreate”. But that the inconsiderate rashness and want of training which shows itself in the doctrines may be made manifest, let us omit all expressions of indignation at his evident blasphemy, and employ in the discussion of this matter a scientific division. For it would be well, I think, to consider in a somewhat careful investigation the exact meaning of the term “generation.” That this expression conveys the meaning of existing as the result of some cause is plain to all, and I suppose there is no need to contend about this point: but since there are different modes of existing as the result of a cause, this difference is what I think ought to receive thorough explanation in our discussion by means of scientific division. Of things which have come into being as the results of some cause we recognize the following differences. Some are the result of material and art, as the fabrics of houses and all other works produced by means of their respective material, where some art gives direction and conducts its purpose to its proper aim. Others are the result of material and nature; for nature orders the generation of animals one from another, effecting her own work by means of the material subsistence in the bodies of the parents; others again are by material efflux. In these the original remains as it was before, and that which flows from it is contemplated by itself, as in the case of the sun and its beam, or the lamp and its radiance, or of scents and ointments, and the quality given off from them. For these, while remaining undiminished in themselves, have each accompanying them the special and peculiar effect which they naturally produce, as the sun his ray, the lamp its brightness, and perfumes the fragrance which they engender in the air. There is also another kind of generation besides these, where the cause is immaterial and incorporeal, but the generation is sensible and takes place through the instrumentality of the body; I mean the generation of the word by the mind. For the mind being in itself incorporeal begets the word by means of sensible instruments. So many are the differences of the term generation, which we discover in a philosophic view of them, that is itself, so to speak, the result of generation.
And now that we have thus distinguished the various modes of generation, it will be time to remark how the benevolent dispensation of the Holy Spirit, in delivering to us the Divine mysteries, imparts that instruction which transcends reason by such methods as we can receive. For the inspired teaching adopts, in order to set forth the unspeakable power of God, all the forms of generation that human intelligence recognizes, yet without including the corporeal senses attaching to the words. For when it speaks of the creative power, it gives to such an energy the name of generation, because its expression must stoop to our low capacity; it does not, however, convey thereby all that we include in creative generation, as time, place, the furnishing of matter, the fitness of instruments, the design in the things that come into being, but it leaves these, and asserts of God in lofty and magnificent language the creation of all existent things, when it says, “He spoke the word and they were made, He commanded and they were created.” Again when it interprets to us the unspeakable and transcendent existence of the Only-begotten from the Father, as the poverty of human intellect is incapable of receiving doctrines which surpass all power of speech and thought, there too it borrows our language and terms Him “Son,”— a name which our usage assigns to those who are born of matter and nature. But just as Scripture, when speaking of generation by creation, does not in the case of God imply that such generation took place by means of any material, affirming that the power of God's will served for material substance, place, time and all such circumstances, even so here too, when using the term Son, it rejects both all else that human nature remarks in generation here below—I mean affections and dispositions and the co-operation of time, and the necessity of place—and, above all, matter, without all which natural generation here below does not take place. But when all such material, temporal and local existence is excluded from the sense of the term “Son,” community of nature alone is left, and for this reason by the title “Son” is declared, concerning the Only-begotten, the close affinity and genuineness of relationship which mark His manifestation from the Father. And since such a kind of generation was not sufficient to implant in us an adequate notion of the ineffable mode of subsistence of the Only-begotten, Scripture avails itself also of the third kind of generation to indicate the doctrine of the Son's Divinity,— that kind, namely, which is the result of material efflux, and speaks of Him as the “brightness of glory,” the “savour of ointment,” the “breath of God;” illustrations which in the scientific phraseology we have adopted we ordinarily designate as material efflux.
But as in the cases alleged neither the birth of the creation nor the force of the term “Son” admits time, matter, place, or affection, so here too the Scripture employing only the illustration of effulgence and the others that I have mentioned, apart from all material conception, with regard to the Divine fitness of such a mode of generation, shows that we must understand by the significance of this expression, an existence at once derived from and subsisting with the Father. For neither is the figure of breath intended to convey to us the notion of dispersion into the air from the material from which it is formed, nor is the figure of fragrance designed to express the passing off of the quality of the ointment into the air, nor the figure of effulgence the efflux which takes place by means of the rays from the body of the sun: but as has been said in all cases, by such a mode of generation is indicated this alone, that the Son is of the Father and is conceived of along with Him, no interval intervening between the Father and Him Who is of the Father. For since of His exceeding loving-kindness the grace of the Holy Spirit so ordered that the divine conceptions concerning the Only-begotten should reach us from many quarters, and so be implanted in us, He added also the remaining kind of generation—that, namely, of the word from the mind. And here the sublime John uses remarkable foresight. That the reader might not through inattention and unworthy conceptions sink to the common notion of “word,” so as to deem the Son to be merely a voice of the Father, he therefore affirms of the Word that He essentially subsisted in the first and blessed nature Itself, thus proclaiming aloud, “In the Beginning was the Word, and with God, and God, and Light, and Life,” and all that the Beginning is, the Word was also.
Source: Against Eunomius (New Advent)