Reply Obj. 2: The Apostle calls Christ the Son of the love of God, inasmuch as He is superabundantly loved by God; not, however, as if love were the principle of the Son's generation.
Reply Obj. 3: The will, as a natural faculty, wills something naturally, as man's will naturally tends to happiness; and likewise God naturally wills and loves Himself; whereas in regard to things other than Himself, the will of God is in a way, undetermined in itself, as above explained (Q. 19, A. 3). Now, the Holy Ghost proceeds as Love, inasmuch as God loves Himself, and hence He proceeds naturally, although He proceeds by mode of will.
Reply Obj. 4: Even as regards the intellectual conceptions of the mind, a return is made to those first principles which are naturally understood. But God naturally understands Himself, and thus the conception of the divine Word is natural.
Reply Obj. 5: A thing is said to be necessary "of itself," and "by reason of another." Taken in the latter sense, it has a twofold meaning: firstly, as an efficient and compelling cause, and thus necessary means what is violent; secondly, it means a final cause, when a thing is said to be necessary as the means to an end, so far as without it the end could not be attained, or, at least, so well attained. In neither of these ways is the divine generation necessary; because God is not the means to an end, nor is He subject to compulsion. But a thing is said to be necessary "of itself" which cannot but be: in this sense it is necessary for God to be; and in the same sense it is necessary that the Father beget the Son. _______________________
THIRD ARTICLE [I, Q. 41, Art. 3]
Whether the Notional Acts Proceed from Something?
Objection 1: It would seem that the notional acts do not proceed from anything. For if the Father begets the Son from something, this will be either from Himself or from something else. If from something else, since that whence a thing is generated exists in what is generated, it follows that something different from the Father exists in the Son, and this contradicts what is laid down by Hilary (De Trin. vii) that, "In them nothing diverse or different exists." If the Father begets the Son from Himself, since again that whence a thing is generated, if it be something permanent, receives as predicate the thing generated therefrom just as we say, "The man is white," since the man remains, when not from white he is made white—it follows that either the Father does not remain after the Son is begotten, or that the Father is the Son, which is false. Therefore the Father does not beget the Son from something, but from nothing.
Obj. 2: Further, that whence anything is generated is the principle regarding what is generated. So if the Father generate the Son from His own essence or nature, it follows that the essence or nature of the Father is the principle of the Son. But it is not a material principle, because in God nothing material exists; and therefore it is, as it were, an active principle, as the begetter is the principle of the one begotten. Thus it follows that the essence generates, which was disproved above (Q. 39, A. 5).
Obj. 3: Further, Augustine says (De Trin. vii, 6) that the three persons are not from the same essence; because the essence is not another thing from person. But the person of the Son is not another thing from the Father's essence. Therefore the Son is not from the Father's essence.
Obj. 4: Further, every creature is from nothing. But in Scripture the Son is called a creature; for it is said (Ecclus. 24:5), in the person of the Wisdom begotten,"I came out of the mouth of the Most High, the first-born before all creatures": and further on (Ecclus. 24:14) it is said as uttered by the same Wisdom, "From the beginning, and before the world was I created." Therefore the Son was not begotten from something, but from nothing. Likewise we can object concerning the Holy Ghost, by reason of what is said (Zech. 12:1): "Thus saith the Lord Who stretcheth forth the heavens, and layeth the foundations of the earth, and formeth the spirit of man within him"; and (Amos 4:13) according to another version [*The Septuagint]: "I Who form the earth, and create the spirit."