Treatise on the Incarnation
Question. 34 - OF THE MODE AND ORDER OF CHRIST'S CONCEPTION (FOUR ARTICLES)
We have now to consider the mode and order of Christ's conception, concerning which there are four points of inquiry:
(1) Whether Christ's body was formed in the first instant of its
conception?
(2) Whether it was animated in the first instant of its conception?
(3) Whether it was assumed by the Word in the first instant of its
conception?
(4) Whether this conception was natural or miraculous?
Art. 1 - Whether Christ's body was formed in the first instant of its conception?
Objection 1: It would seem that Christ's body was not formed in the
first instant of its conception. For it is written (Jn. 2:20): "Six-and-forty years was this Temple in building"; on which words Augustine comments as follows (De Trin. iv): "This number applies manifestly to the perfection of our Lord's body." He says, further (QQ. lxxxiii, qu. 56): "It is not without reason that the Temple, which was a type of His body, is said to have been forty-six years in building: so that as many years as it took to build the Temple, in so many days was our Lord's body perfected." Therefore Christ's body was not perfectly formed in the first instant of its conception.
Objection 2: Further, there was need of local movement for the
formation of Christ's body in order that the purest blood of the
Virgin's body might be brought where generation might aptly take place. Now, no body can be moved locally in an instant: since the time taken in movement is divided according to the division of the thing moved, as is proved Phys. vi. Therefore Christ's body was not formed in an instant.
Objection 3: Further, Christ's body was formed of the purest blood of
the Virgin, as stated above ([4151]Q[31], A[5]). But that matter could
not be in the same instant both blood and flesh, because thus matter
would have been at the same time the subject of two forms. Therefore
the last instant in which it was blood was distinct from the first
instant in which it was flesh. But between any two instants there is an
interval of time. Therefore Christ's body was not formed in an instant, but during a space of time.
Objection 4: Further, as the augmentative power requires a fixed time
for its act, so also does the generative power: for both are natural
powers belonging to the vegetative soul. But Christ's body took a fixed
time to grow, like the bodies of other men: for it is written (Lk. 2:52) that He "advanced in wisdom and age." Therefore it seems for the same reason that the formation of His body, since that, too, belongs to the generative power, was not instantaneous, but took a fixed time, like the bodies of other men.
On the contrary, Gregory says (Moral. xviii): "As soon as the angel
announced it, as soon as the Spirit came down, the Word was in the
womb, within the womb the Word was made flesh."
I answer that, In the conception of Christ's body three points may be
considered: first, the local movement of the blood to the place of
generation; secondly, the formation of the body from that matter; thirdly, the development whereby it was brought to perfection of quantity. of these, the second is the conception itself; the first is a preamble; the third, a result of the conception.
Now, the first could not be instantaneous: since this would be contrary
to the very nature of the local movement of any body whatever, the
parts of which come into a place successively. The third also requires
a succession of time: both because there is no increase without local
movement, and because increase is effected by the power of the soul
already informing the body, the operation of which power is subject to
time.