IV. His Ascension refines our Faith: the ministering of angels to Him shows the extent of His authority
The Son of Man and Son of God, therefore, dearly-beloved, then attained a more excellent and holier fame, when He betook Himself back to the glory of the Father's Majesty, and in an ineffable manner began to be nearer to the Father in respect of His Godhead, after having become farther away in respect of His manhood. A better instructed faith then began to draw closer to a conception of the Son's equality with the Father without the necessity of handling the corporeal substance in Christ, whereby He is less than the Father, since, while the Nature of the glorified Body still remained the faith of believers was called upon to touch not with the hand of flesh, but with the spiritual understanding the Only-begotten, Who was equal with the Father.
Hence comes that which the Lord said after His Resurrection, when Mary Magdalene, representing the Church, hastened to approach and touch Him: “Touch Me not, for I have not yet ascended to My Father:” that is, I would not have you come to Me as to a human body, nor yet recognize Me by fleshly perceptions: I put you off for higher things, I prepare greater things for you: when I have ascended to My Father, then you shall handle Me more perfectly and truly, for you shall grasp what you can not touch and believe what you can not see.
But when the disciples' eyes followed the ascending Lord to heaven with upward gaze of earnest wonder, two angels stood by them in raiment shining with wondrous brightness, who also said, “You men of Galilee, why do you stand gazing into heaven? This Jesus Who was taken up from you into heaven shall so come as you saw Him going into heaven.” By which words all the sons of the Church were taught to believe that Jesus Christ will come visibly in the same Flesh wherewith He ascended, and not to doubt that all things are subjected to Him on Whom the ministry of angels had waited from the first beginning of His Birth.
For, as an angel announced to the blessed Virgin that Christ should be conceived by the Holy Ghost, so the voice of heavenly beings sang of His being born of the Virgin also to the shepherds. As messengers from above were the first to attest His having risen from the dead, so the service of angels was employed to foretell His coming in very Flesh to judge the world, that we might understand what great powers will come with Him as Judge, when such great ones ministered to Him even in being judged.
Source: Sermons (New Advent)