Whether the Father and the Son are one principle of the Holy Ghost?

Objections

Objection 1 : It would seem that the Father and the Son are not one principle of the Holy Ghost. For the Holy Ghost does not proceed from the Father and the Son as they are one; not as they are one in nature, for the Holy Ghost would in that way proceed from Himself, as He is one in nature with Them; nor again inasmuch as they are united in any one property, for it is clear that one property cannot belong to two subjects. Therefore the Holy Ghost proceeds from the Father and the Son as distinct from one another. Therefore the Father and the Son are not one principle of the Holy Ghost.
Objection 2 : Further, in this proposition "the Father and the Son are one principle of the Holy Ghost," we do not designate personal unity, because in that case the Father and the Son would be one person; nor again do we designate the unity of property, because if one property were the reason of the Father and the Son being one principle of the Holy Ghost, similarly, on account of His two properties, the Father would be two principles of the Son and of the Holy Ghost, which cannot be admitted. Therefore the Father and the Son are not one principle of the Holy Ghost.
Objection 3 : Further, the Son is not one with the Father more than is the Holy Ghost. But the Holy Ghost and the Father are not one principle as regards any other divine person. Therefore neither are the Father and the Son.
Objection 4 : Further, if the Father and the Son are one principle of the Holy Ghost, this one is either the Father or it is not the Father. But we cannot assert either of these positions because if the one is the Father, it follows that the Son is the Father; and if the one is not the Father, it follows that the Father is not the Father. Therefore we cannot say that the Father and the Son are one principle of the Holy Ghost.
Objection 5 : Further, if the Father and the Son are one principle of the Holy Ghost, it seems necessary to say, conversely, that the one principle of the Holy Ghost is the Father and the Son. But this seems to be false; for this word "principle" stands either for the person of the Father, or for the person of the Son; and in either sense it is false. Therefore this proposition also is false, that the Father and the Son are one principle of the Holy Ghost.
Objection 6 : Further, unity in substance makes identity. So if the Father and the Son are the one principle of the Holy Ghost, it follows that they are the same principle; which is denied by many. Therefore we cannot grant that the Father and the Son are one principle of the Holy Ghost.
Objection 7 : Further, the Father, Son and Holy Ghost are called one Creator, because they are the one principle of the creature. But the Father and the Son are not one, but two Spirators, as many assert; and this agrees also with what Hilary says (De Trin. ii) that "the Holy Ghost is to be confessed as proceeding from Father and Son as authors." Therefore the Father and the Son are not one principle of the Holy Ghost.