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 Psalm 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 Colossians 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 John 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 Psalm 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 John 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 Hebrews 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.
Source: Summa Theologica (New Advent)