Whether Christ could merit in the first instant of His conception?
Objection 1: It would seem that Christ could not merit in the first instant of His conception. For the free-will bears the same relation to merit as to demerit. But the devil could not sin in the first instant of his creation, as was shown in the FP, Q[63], A[5]. Therefore neither could Christ's soul merit in the first instant of its creation---that is, in the first instant of Christ's conception.
Objection 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 FS, Q[109], A[5]; FS, 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.
Objection 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 to Objection 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 to that which is according to nature; because that which is beside nature is an exception to nature." Therefore the free-will of a creature can be moved to good meritoriously in the first instant of its creation, but not to evil sinfully; provided, however, its nature be unimpaired.
Reply to Objection 2: That which man has at the first moment of his creation, in the ordinary course of nature, is natural to him. but nothing hinders a creature from receiving from God a gift of grace at the very beginning of its creation. In this way did Christ's soul in the first instant of its creation receive grace by which it could merit. And for this reason is that grace, by way of a certain likeness, said to be natural to this Man, as explained by Augustine (Enchiridion xl).
Reply to Objection 3: Nothing prevents the same thing belonging to someone from several causes. And thus it is that Christ was able by subsequent actions and sufferings to merit the glory of immortality, which He also merited in the first instant of His conception: not, indeed, so that it became thereby more due to Him than before, but so that it was due to Him from more causes than before.
Whether Christ was a perfect comprehensor in the first instant of His conception?
Objection 1: It would seem that Christ was not a perfect comprehensor in the first instant of His conception. For merit precedes reward, as fault precedes punishment. But Christ merited in the first instant of His conception, as stated above (A[3]). Since, therefore, the state of comprehension is the principal reward, it seems that Christ was not a comprehensor in the first instant of His conception.
Objection 2: Further, our Lord said ( Lk. 24:26 ): "Ought not Christ to have suffered these things, and so to enter into His glory?" But glory belongs to the state of comprehension. Therefore Christ was not in the state of comprehension in the first instant of His conception, when as yet He had not suffered.
Objection 3: Further, what befits neither man nor angel seems proper to God; and therefore is not becoming to Christ as man. But to be always in the state of beatitude befits neither man nor angel: for if they had been created in beatitude, they would not have sinned afterwards. Therefore Christ, as man, was not in the state of beatitude in the first instant of His conception.
On the contrary, It is written ( Ps. 64:5 ): "Blessed is he whom Thou hast chosen, end taken to Thee"; which words, according to the gloss, refer to Christ's human nature, which "was taken by the Word of God unto the unity of Person." But human nature was taken by the Word of God in the first instant of His conception. Therefore, in the first instant of His conception, Christ, as man, was in the state of beatitude; which is to be a comprehensor.
I answer that, As appears from what was said above (A[3]), it was unbecoming that in His conception Christ should receive merely habitual grace without the act. Now, He received grace "not by measure" ( Jn. 3:34 ), as stated above (Q[7], A[11]). But the grace of the "wayfarer," being short of that of the "comprehensor," is in less measure than that of the comprehensor. Wherefore it is manifest that in the first instant of His conception Christ received not only as much grace as comprehensors have, but also greater than that which they all have. And because that grace was not without its act, it follows that He was a comprehensor in act, seeing God in His Essence more clearly than other creatures.
Reply to Objection 1: As stated above (Q[19], A[3]), Christ did not merit the glory of the soul, in respect of which He is said to have been a comprehensor, but the glory of the body, to which He came through His Passion.
Wherefore the reply to the Second Objection is clear.
Reply to Objection 3: Since Christ was both God and man, He had, even in His humanity, something more than other creatures---namely, that He was in the state of beatitude from the very beginning.