From Catechetical Lecture 4:
But when Jesus had finished His course of patient endurance, and had redeemed mankind from their sins, He ascended again into the heavens, a cloud receiving Him up: and as He went up Angels were beside Him, and Apostles were beholding. But if any man disbelieves the words which I speak, let him believe the actual power of the things now seen. All kings when they die have their power extinguished with their life: but Christ crucified is worshipped by the whole world. We proclaim The Crucified, and the devils tremble now. Many have been crucified at various times; but of what other who was crucified did the invocation ever drive the devils away?
Let us, therefore, not be ashamed of the Cross of Christ; but though another hide it, do thou openly seal it upon your forehead, that the devils may behold the royal sign and flee trembling far away. Make then this sign at eating and drinking, at sitting, at lying down, at rising up, at speaking, at walking: in a word, at every act. For He who was here crucified is in heaven above. If after being crucified and buried He had remained in the tomb, we should have had cause to be ashamed; but, in fact, He who was crucified on Golgotha here, has ascended into heaven from the Mount of Olives on the East. For after having gone down hence into Hades, and come up again to us, He ascended again from us into heaven, His Father addressing Him, and saying, "Sit on My right hand, until I make Your enemies Your footstool."
From Catechetical Lecture 14:
The course of instruction in the Faith would lead me to speak of the Ascension also; but the grace of God so ordered it, that you heard most fully concerning it, as far as our weakness allowed, yesterday, on the Lord's day; since, by the providence of divine grace, the course of the Lessons in Church included the account of our Saviour's going up into the heavens ; and what was then said was spoken principally for the sake of all, and for the assembled body of the faithful, yet especially for your sake. But the question is, did you attend to what was said? For you know that the words which come next in the Creed teach you to believe in Him Who rose again the third day, and ascended into Heaven, and sat down on the right hand of the Father. I suppose then certainly that you remember the exposition; yet I will now again cursorily put you in mind of what was then said. Remember what is distinctly written in the Psalms, "God is gone up with a shout;" remember that the divine powers also said to one another, "Lift up your gates, you Princes," and the rest; remember also the Psalm which says, "He ascended on high, He led captivity captive;" remember the Prophet who said, "Who builds His ascension unto heaven;" and all the other particulars mentioned yesterday because of the gainsaying of the Jews.
For when they speak against the ascension of the Saviour, as being impossible, remember the account of the carrying away of Habakkuk: for if Habakkuk was transported by an Angel, being carried by the hair of his head , much rather was the Lord of both Prophets and Angels, able by His own power to make His ascent into the Heavens on a cloud from the Mount of Olives. Wonders like this you may call to mind, but reserve the preeminence for the Lord, the Worker of wonders; for the others were borne up, but He bears up all things. Remember that Enoch was translated [Hebrews 11:5]; but Jesus ascended: remember what was said yesterday concerning Elias, that Elias was taken up in a chariot of fire [2 Kings 2:11]; but that "the chariots of" Christ "are ten thousand-fold even thousands upon thousands:" and that Elias was taken up, towards the east of Jordan; but that Christ ascended at the east of the brook Cedron: and that Elias went "as into heaven;" but Jesus, into heaven: and that Elias said that a double portion in the Holy Spirit should be given to his holy disciple; but that Christ granted to His own disciples so great enjoyment of the grace of the Holy Ghost, as not only to have It in themselves, but also, by the laying on of their hands, to impart the fellowship of It to them who believed.
And when you have thus wrestled against the Jews — when you have worsted them by parallel instances, then come further to the pre-eminence of the Saviour's glory; namely, that they were the servants, but He the Son of God. And thus you will be reminded of His pre-eminence, by the thought that a servant of Christ was caught up to the third heaven. For if Elias attained as far as the first heaven, but Paul as far as the third, the latter, therefore, has obtained a more honourable dignity. Be not ashamed of your Apostles; they are not inferior to Moses, nor second to the Prophets; but they are noble among the noble, yea, nobler still. For Elias truly was taken up into heaven; but Peter has the keys of the kingdom of heaven, having received the words, "Whatsoever you shall loose on earth shall be loosed in heaven." [Matthew 16:19] Elias was taken up only to heaven; but Paul both into heaven, and into paradise (for it behooved the disciples of Jesus to receive more manifold grace), "and heard unspeakable words, which it is not lawful for man to utter." But Paul came down again from above, not because he was unworthy to abide in the third heaven, but in order that after having enjoyed things above man's reach, and descended in honour, and having preached Christ, and died for His sake, he might receive also the crown of martyrdom. But I pass over the other parts of this argument, of which I spoke yesterday in the Lord's-day congregation; for with understanding hearers, a mere reminder is sufficient for instruction.
But remember also what I have often said concerning the Son's sitting at the right hand of the Father; because of the next sentence in the Creed, which says, "and ascended into Heaven, and sat down at the right hand of the Father." Let us not curiously pry into what is properly meant by the throne; for it is incomprehensible: but neither let us endure those who falsely say, that it was after His Cross and Resurrection and Ascension into heaven, that the Son began to sit on the right hand of the Father. For the Son gained not His throne by advancement; but throughout His being (and His being is by an eternal generation) He also sits together with the Father. And this throne the Prophet Isaiah having beheld before the incarnate coming of the Saviour, says, "I saw the Lord sitting on a throne, high and lifted up" [Isaiah 6:1], and the rest. "For the Father no man has seen at any time" [John 1:18], and He who then appeared to the Prophet was the Son. The Psalmist also says, "Your throne is prepared of old; You are from everlasting." Though then the testimonies on this point are many, yet because of the lateness of the time, we will content ourselves even with these.
But now I must remind you of a few things out of many which are spoken concerning the Son's sitting at the right hand of the Father. For the hundred and ninth Psalm says plainly, "The Lord said unto my Lord, Sit on My right hand, until I make Your enemies Your footstool." And the Saviour, confirming this saying in the Gospels, says that "David spoke not these things of himself, but from the inspiration of the Holy Ghost, saying, How then does David in the Spirit call Him Lord, saying, The Lord said unto my Lord, Sit on My right hand?" [Matthew 22:43] And the rest. And in the Acts of the Apostles, Peter on the day of Pentecost standing with the Eleven [Acts 2:34], and discoursing to the Israelites, has in very words cited this testimony from the hundred and ninth Psalm.
But I must remind you also of a few other testimonies in like manner concerning the Son's sitting at the right hand of the Father. For in the Gospel according to Matthew it is written, "Nevertheless, I say unto you, Henceforth you shall see the Son of Man sitting on the right hand of power" [Matthew 26:64], and the rest: in accordance with which the Apostle Peter also writes, "By the Resurrection of Jesus Christ, who is on the right hand of God, having gone into heaven." [1 Peter 3:22] And the Apostle Paul, writing to the Romans, says, "It is Christ that died, yea rather, that is risen again, who is even at the right hand of God." [Romans 8:34] And charging the Ephesians, he thus speaks, "According to the working of His mighty power, which He wrought in Christ when He raised Him from the dead, and set Him at His own right hand" [Ephesians 1:19-20]; and the rest. And the Colossians he taught thus, "If you then be risen with Christ, seek the things above, where Christ is seated at the right hand of God." [Colossians 3:1] And in the Epistle to the Hebrews he says, "When He had made purification of our sins, He sat down on the right hand of the Majesty on high." [Hebrews 1:3[ And again, "But unto which of the Angels has He said at any time, Sit thou at My right hand, until I make your enemies your footstool?" And again, "But He, when He had offered one sacrifice for all men, for ever sat down on the right hand of God; from henceforth expecting till His enemies be made His footstool." And again, "Looking unto Jesus, the author and perfecter of our faith; Who for the joy that was set before Him endured the Cross, despising shame, and is set down on the right hand of the throne of God."
And though there are many other texts concerning the sitting of the Only-begotten on the right hand of God, yet these may suffice us at present; with a repetition of my remark, that it was not after His coming in the flesh that He obtained the dignity of this seat; no, for even before all ages, the Only-begotten Son of God, our Lord Jesus Christ, ever possesses the throne on the right hand of the Father. Now may He Himself, the God of all, who is Father of the Christ, and our Lord Jesus Christ, who came down, and ascended, and sits together with the Father, watch over your souls; keep unshaken and unchanged your hope in Him who rose again; raise you together with Him from your dead sins unto His heavenly gift; count you worthy to be caught up in the clouds, "to meet the Lord in the air" [1 Thessalonians 4:17], in His fitting time; and, until that time arrive of His glorious second advent, write all your names in the Book of the living, and having written them, never blot them out (for the names of many, who fall away, are blotted out); and may He grant to all of you to believe in Him who rose again, and to look for Him who is gone up, and is to come again, (to come, but not from the earth; for be on your guard, O man, because of the deceivers who are to come;) Who sits on high, and is here present together with us, beholding the order of each, and the steadfastness of his faith. [Colossians 2:5] For think not that because He is now absent in the flesh, He is therefore absent also in the Spirit. He is here present in the midst of us, listening to what is said of Him, and beholding your inward thoughts, and trying the reins and hearts — who also is now ready to present those who are coming to baptism, and all of you, in the Holy Ghost to the Father, and to say, "Behold, I and the children whom God has given Me:" — To whom be glory for ever. Amen.