either could Christ's soul merit in the first instant of
its creation--that is, in the first instant of Christ's conception.

Obj. 2: Further, that which man has in the first instant of his
conception seems to be natural to him: for it is in this that his
natural generation is terminated. But we do not merit by what is
natural to us, as is clear from what has been said in the Second Part
(I-II, Q. 109, A. 5; Q. 114, A. 2). Therefore it seems that the use
of free-will, which Christ as man had in the first instant of His
conception, was not meritorious.

Obj. 3: Further, that which a man has once merited he makes, in a
way, his own: consequently it seems that he cannot merit the same
thing again: for no one merits what is already his. If, therefore,
Christ merited in the first instant of His conception, it follows
that afterwards He merited nothing. But this is evidently untrue.
Therefore Christ did not merit in the first instant of His conception.

_On the contrary,_ Augustine [*Paterius, Expos. Vet. et Nov. Test.
super Ex. 40] says: "Increase of merit was absolutely impossible to
the soul of Christ." But increase of merit would have been possible
had He not merited in the first instant of His conception. Therefore
Christ merited in the first instant of His conception.

_I answer that,_ As stated above (A. 1), Christ was sanctified by
grace in the first instant of His conception. Now, sanctification is
twofold: that of adults who are sanctified in consideration of their
own act; and that of infants who are sanctified in consideration of,
not their own act of faith, but that of their parents or of the
Church. The former sanctification is more perfect than the latter:
just as act is more perfect than habit; and "that which is by itself,
than that which is by another" [*Aristotle, _Phys._ viii]. Since,
therefore, the sanctification of Christ was most perfect, because He
was so sanctified that He might sanctify others; consequently He was
sanctified by reason of His own movement of the free-will towards
God. Which movement, indeed, of the free-will is meritorious.
Consequently, Christ did merit in the first instant of His conception.

Reply Obj. 1: Free-will does not bear the same relation to good as to
evil: for to good it is related of itself, and naturally; whereas to
evil it is related as to a defect, and beside nature. Now, as the
Philosopher says (De Coelo ii, text. 18): "That which is beside
nature is subsequent