Summa Theologica, by St. Thomas Aquinas, [1947], at sacred-texts.com
We must now consider Christ's knowledge; concerning which the consideration will be twofold. First, of Christ's knowledge in general; secondly, of each particular kind of knowledge He had.
Under the first head there are four points of inquiry:
(1) Whether Christ had any knowledge besides the Divine?
(2) Whether He had the knowledge which the blessed or comprehensors have?
(3) Whether He had an imprinted or infused knowledge?
(4) Whether He had any acquired knowledge?
Objection 1: It would seem that in Christ there was no knowledge except the Divine. For knowledge is necessary that things may be known thereby. But by His Divine knowledge Christ knew all things. Therefore any other knowledge would have been superfluous in Him.
Objection 2: Further, the lesser light is dimmed by the greater. But all created knowledge in comparison with the uncreated knowledge of God is as the lesser to the greater light. Therefore there shone in Christ no other knowledge except the Divine.
Objection 3: Further, the union of the human nature with the Divine took place in the Person, as is clear from Q[2], A[2]. Now, according to some there is in Christ a certain "knowledge of the union," whereby Christ knew what belongs to the mystery of the Incarnation more fully than anyone else. Hence, since the personal union contains two natures, it would seem that there are not two knowledges in Christ, but one only, pertaining to both natures.
On the contrary, Ambrose says (De Incarnat. vii): "God assumed the perfection of human nature in the flesh; He took upon Himself the sense of man, but not the swollen sense of the flesh." But created knowledge pertains to the sense of man. Therefore in Christ there was created knowledge.
I answer that, As said above (Q[5]), the Son of God assumed an entire human nature, i.e. not only a body, but also a soul, and not only a sensitive, but also a rational soul. And therefore it behooved Him to have created knowledge, for three reasons. First, on account of the soul's perfection. For the soul, considered in itself, is in potentiality to knowing intelligible things. since it is like "a tablet on which nothing is written," and yet it may be written upon through the possible intellect, whereby it may become all things, as is said De Anima iii, 18. Now what is in potentiality is imperfect unless reduced to act. But it was fitting that the Son of God should assume, not an imperfect, but a perfect human nature, since the whole human race was to be brought back to perfection by its means. Hence it behooved the soul of Christ to be perfected by a knowledge, which would be its proper perfection. And therefore it was necessary that there should be another knowledge in Christ besides the Divine knowledge, otherwise the soul of Christ would have been more imperfect than the souls of the rest of men. Secondly, because, since everything is on account of its operation, as stated De Coel. ii, 17, Christ would have had an intellective soul to no purpose if He had not understood by it; and this pertains to created knowledge. Thirdly, because some created knowledge pertains to the nature of the human soul, viz. that whereby we naturally know first principles; since we are here taking knowledge for any cognition of the human intellect. Now nothing natural was wanting to Christ, since He took the whole human nature, as stated above (Q[5]). And hence the Sixth Council [*Third Council of Constantinople, Act. 4] condemned the opinion of those who denied that in Christ there are two knowledges or wisdoms.
Reply to Objection 1: Christ knew all things with the Divine knowledge by an uncreated operation which is the very Essence of God; since God's understanding is His substance, as the Philosopher proves (Metaph. xii, text. 39). Hence this act could not belong to the human soul of Christ, seeing that it belongs to another nature. Therefore, if there had been no other knowledge in the soul of Christ, it would have known nothing; and thus it would have been assumed to no purpose, since everything is on account of its operation.
Reply to Objection 2: If the two lights are supposed to be in the same order, the lesser is dimmed by the greater, as the light of the sun dims the light of a candle, both being in the class of illuminants. But if we suppose two lights, one of which is in the class of illuminants and the other in the class of illuminated, the lesser light is not dimmed by the greater, but rather is strengthened, as the light of the air by the light of the sun. And in this manner the light of knowledge is not dimmed, but rather is heightened in the soul of Christ by the light of the Divine knowledge, which is "the true light which enlighteneth every man that cometh into this world," as is written Jn. 1:9.
Reply to Objection 3: On the part of what are united we hold there is a knowledge in Christ, both as to His Divine and as to His human nature; so that, by reason of the union whereby there is one hypostasis of God and man, the things of God are attributed to man, and the things of man are attributed to God, as was said above (Q[3], AA[1],6). But on the part of the union itself we cannot admit any knowledge in Christ. For this union is in personal being, and knowledge belongs to person only by reason of a nature.
Objection 1: It would seem that in Christ there was not the knowledge of the blessed or comprehensors. For the knowledge of the blessed is a participation of Divine light, according to Ps. 35:10: "In Thy light we shall see light." Now Christ had not a participated light, but He had the Godhead Itself substantially abiding in Him, according to Col. 2:9: "For in Him dwelleth all the fulness of the Godhead corporeally." Therefore in Christ there was not the knowledge of the blessed.
Objection 2: Further, the knowledge of the blessed makes them blessed, according to Jn. 17:3: "This is eternal life: that they may know Thee, the only true God, and Jesus Christ Whom Thou hast sent." But this Man was blessed through being united to God in person, according to Ps. 64:5: "Blessed is He Whom Thou hast chosen and taken to Thee." Therefore it is not necessary to suppose the knowledge of the blessed in Him.
Objection 3: Further, to man belongs a double knowledge---one by nature, one above nature. Now the knowledge of the blessed, which consists in the vision of God, is not natural to man, but above his nature. But in Christ there was another and much higher supernatural knowledge, i.e. the Divine knowledge. Therefore there was no need of the knowledge of the blessed in Christ.
On the contrary, The knowledge of the blessed consists in the knowledge of God. But He knew God fully, even as He was man, according to Jn. 8:55: "I do know Him, and do keep His word." Therefore in Christ there was the knowledge of the blessed.
I answer that, What is in potentiality is reduced to act by what is in act; for that whereby things are heated must itself be hot. Now man is in potentiality to the knowledge of the blessed, which consists in the vision of God; and is ordained to it as to an end; since the rational creature is capable of that blessed knowledge, inasmuch as he is made in the image of God. Now men are brought to this end of beatitude by the humanity of Christ, according to Heb. 2:10: "For it became Him, for Whom are all things, and by Whom are all things, Who had brought many children unto glory, to perfect the author of their salvation by His passion." And hence it was necessary that the beatific knowledge, which consists in the vision of God, should belong to Christ pre-eminently, since the cause ought always to be more efficacious than the effect.
Reply to Objection 1: The Godhead is united to the manhood of Christ in Person, not in essence or nature; yet with the unity of Person remains the distinction of natures. And therefore the soul of Christ, which is a part of human nature, through a light participated from the Divine Nature, is perfected with the beatific knowledge whereby it sees God in essence.
Reply to Objection 2: By the union this Man is blessed with the uncreated beatitude, even as by the union He is God; yet besides the uncreated beatitude it was necessary that there should be in the human nature of Christ a created beatitude, whereby His soul was established in the last end of human nature.
Reply to Objection 3: The beatific vision and knowledge are to some extent above the nature of the rational soul, inasmuch as it cannot reach it of its own strength; but in another way it is in accordance with its nature, inasmuch as it is capable of it by nature, having been made to the likeness of God, as stated above. But the uncreated knowledge is in every way above the nature of the human soul.
Objection 1: It would seem that there was not in Christ another infused knowledge besides the beatific knowledge. For all other knowledge compared to the beatific knowledge is like imperfect to perfect. But imperfect knowledge is removed by the presence of perfect knowledge, as the clear "face-to-face" vision removes the enigmatical vision of faith, as is plain from 1 Cor. 13:10, 12 Since, therefore, in Christ there was the beatific knowledge, as stated above (A[2]), it would seem that there could not be any other imprinted knowledge.
Objection 2: Further, an imperfect mode of cognition disposes towards a more perfect, as opinion, the result of dialectical syllogisms, disposes towards science, which results from demonstrative syllogisms. Now, when perfection is reached, there is no further need of the disposition, even as on reaching the end motion is no longer necessary. Hence, since every created cognition is compared to beatific cognition, as imperfect to perfect and as disposition to its term, it seems that since Christ had beatific knowledge, it was not necessary for Him to have any other knowledge.
Objection 3: Further, as corporeal matter is in potentiality to sensible forms, so the possible intellect is in potentiality to intelligible forms. Now corporeal matter cannot receive two forms at once! one more perfect and the other less perfect. Therefore neither can the soul receive a double knowledge at once, one more perfect and the other less perfect; and hence the same conclusion as above.
On the contrary, It is written (Col. 2:3) that in Christ "are hid all the treasures of wisdom and knowledge."
I answer that, As stated above (A[1]), it was fitting that the human nature assumed by the Word of God should not be imperfect. Now everything in potentiality is imperfect unless it be reduced to act. But the passive intellect of man is in potentiality to all intelligible things. and it is reduced to act by intelligible species, which are its completive forms, as is plain from what is said De Anima iii, 32,38. And hence we must admit in the soul of Christ an infused knowledge, inasmuch as the Word of God imprinted upon the soul of Christ, which is personally united to Him, intelligible species of all things to which the possible intellect is in potentiality; even as in the beginning of the creation of things, the Word of God imprinted intelligible species upon the angelic mind, as is clear from Augustine (Gen. ad lit. ii, 8). And therefore, even as in the angels, according to Augustine (Gen. ad lit. iv, 22,24,30), there is a double knowledge---one the morning knowledge, whereby they know things in the Word; the other the evening knowledge, whereby they know things in their proper natures by infused species; so likewise, besides the Divine and uncreated knowledge in Christ, there is in His soul a beatific knowledge, whereby He knows the Word, and things in the Word; and an infused or imprinted knowledge, whereby He knows things in their proper nature by intelligible species proportioned to the human mind.
Reply to Objection 1: The imperfect vision of faith is essentially opposed to manifest vision, seeing that it is of the essence of faith to have reference to the unseen, as was said above (SS, Q[1], A[4]). But cognition by infused species includes no opposition to beatific cognition. Therefore there is no parity.
Reply to Objection 2: Disposition is referred to perfection in two ways: first, as a way leading to perfection; secondly, as an effect proceeding from perfection; thus matter is disposed by heat to receive the form of fire, and, when this comes, the heat does not cease, but remains as an effect of this form. So, too, opinion caused by a dialectical syllogism is a way to knowledge, which is acquired by demonstration, yet, when this has been acquired, there may still remain the knowledge gained by the dialectical syllogism, following, so to say, the demonstrative knowledge, which is based on the cause, since he who knows the cause is thereby enabled the better to understand the probable signs from which dialectical syllogisms proceed. So likewise in Christ, together with the beatific knowledge, there still remains infused knowledge, not as a way to beatitude, but as strengthened by beatitude.
Reply to Objection 3: The beatific knowledge is not by a species, that is a similitude of the Divine Essence, or of whatever is known in the Divine Essence, as is plain from what has been said in the FP, Q[12], A[2]; but it is a knowledge of the Divine Essence immediately, inasmuch as the Divine Essence itself is united to the beatified mind as an intelligible to an intelligent being; and the Divine Essence is a form exceeding the capacity of any creature whatsoever. Hence, together with this super-exceeding form, there is nothing to hinder from being in the rational mind, intelligible species, proportioned to its nature.
Objection 1: It would seem that in Christ there was no empiric and acquired knowledge. For whatever befitted Christ, He had most perfectly. Now Christ did not possess acquired knowledge most perfectly, since He did not devote Himself to the study of letters, by which knowledge is acquired in its perfection; for it is said (Jn. 7:15): "The Jews wondered, saying: How doth this Man know letters, having never learned?" Therefore it seems that in Christ there was no acquired knowledge.
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[1], 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[3]; D, xviii, A[3]), 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[12], A[4].
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.