Objection 2: Further, nothing can be added to what is full. But the power of Christ's soul was filled with intelligible species divinely infused, as was said above (A.3). Therefore no acquired species could accrue to His soul.
Objection 3: Further, he who already has the habit of knowledge, acquires no new habit, through what he receives from the senses (otherwise two forms of the same species would be in the same thing together); but the habit which previously existed is strengthened and increased. Therefore, since Christ had the habit of infused knowledge, it does not seem that He acquired a new knowledge through what He perceived by the senses.
On the contrary, It is written (Heb.5:8): "Whereas . . . He was the Son of God, He learned obedience by the things which He suffered," i.e. "experienced," says a gloss. Therefore there was in the soul of Christ an empiric knowledge, which is acquired knowledge.
I answer that, As is plain from A, nothing that God planted in our nature was wanting to the human nature assumed by the Word of God. Now it is manifest that God planted in human nature not only a passive, but an active intellect. Hence it is necessary to say that in the soul of Christ there was not merely a passive, but also an active intellect. But if in other things God and nature make nothing in vain, as the Philosopher says (De Coel. i, 31; ii, 59), still less in the soul of Christ is there anything in vain. Now what has not its proper operation is useless, as is said in De Coel. ii, 17. Now the proper operation of the active intellect is to make intelligible species in act, by abstracting them from phantasms; hence, it is said (De Anima iii, 18) that the active intellect is that "whereby everything is made actual." And thus it is necessary to say that in Christ there were intelligible species received in the passive intellect by the action of the active intellect -- -which means that there was acquired knowledge in Him, which some call empiric. And hence, although I wrote differently (Sent. iii, D, xiv, A; D, xviii, A), it must be said that in Christ there was acquired knowledge, which is properly knowledge in a human fashion, both as regards the subject receiving and as regards the active cause. For such knowledge springs from Christ's active intellect, which is natural to the human soul. But infused knowledge is attributed to the soul, on account of a light infused from on high, and this manner of knowing is proportioned to the angelic nature. But the beatific knowledge, whereby the very Essence of God is seen, is proper and natural to God alone, as was said in the FP, Q, A.
Reply to Objection 1: Since there is a twofold way of acquiring knowledge -- -by discovery and by being taught -- -the way of discovery is the higher, and the way of being taught is secondary. Hence it is said (Ethic. i, 4): "He indeed is the best who knows everything by himself: yet he is good who obeys him that speaks aright." And hence it was more fitting for Christ to possess a knowledge acquired by discovery than by being taught, especially since He was given to be the Teacher of all, according to Joel 2:23: "Be joyful in the Lord your God, because He hath given you a Teacher of justice."
Reply to Objection 2: The human mind has two relations -- -one to higher things, and in this respect the soul of Christ was full of the infused knowledge. The other relation is to lower things, i.e. to phantasms, which naturally move the human mind by virtue of the active intellect. Now it was necessary that even in this respect the soul of Christ should be filled with knowledge, not that the first fulness was insufficient for the human mind in itself, but that it behooved it to be also perfected with regard to phantasms.
Reply to Objection 3: Acquired and infused habits are not to be classed together; for the habit of knowledge is acquired by the relation of the human mind to phantasms; hence, another habit of the same kind cannot be again acquired. But the habit of infused knowledge is of a different nature, as coming down to the soul from on high, and not from phantasms. And hence there is no parity between these habits.