of His Mother in time:
indeed, these two nativities differ specifically. Wherefore, as to
this, we must say that there are various filiations, one temporal and
the other eternal. Since, however, the subject of filiation is
neither the nature nor part of the nature, but the person or
hypostasis alone; and since in Christ there is no other hypostasis or
person than the eternal, there can be no other filiation in Christ
but that which is in the eternal hypostasis. Now, every relation
which is predicated of God from time does not put something real in
the eternal God, but only something according to our way of thinking,
as we have said in the First Part (Q. 13, A. 7). Therefore the
filiation by which Christ is referred to His Mother cannot be a real
relation, but only a relation of reason.

Consequently each opinion is true to a certain extent. For if we
consider the adequate causes of filiation, we must needs say that
there are two filiations in respect of the twofold nativity. But if
we consider the subject of filiation, which can only be the eternal
suppositum, then no other than the eternal filiation in Christ is a
real relation. Nevertheless, He has the relation of Son in regard to
His Mother, because it is implied in the relation of motherhood to
Christ. Thus God is called Lord by a relation which is implied in the
real relation by which the creature is subject to God. And although
lordship is not a real relation in God, yet is He really Lord through
the real subjection of the creature to Him. In the same way Christ is
really the Son of the Virgin Mother through the real relation of her
motherhood to Christ.

Reply Obj. 1: Temporal nativity would cause a real temporal filiation
in Christ if there were in Him a subject capable of such filiation.
But this cannot be; since the eternal suppositum cannot be receptive
of a temporal relation, as stated above. Nor can it be said that it
is receptive of temporal filiation by reason of the human nature,
just as it is receptive of the temporal nativity; because human
nature would need in some way to be the subject of filiation, just as
in a way it is the subject of nativity; for since an Ethiopian is
said to be white by reason of his teeth, it must be that his teeth
are the subject of whiteness. But human nature can nowise be the
subject of filiation, because this relation regards directly the
person.

Reply Obj. 2: Eternal filiation does not depend on a temporal mother,
bu