[The following selctions are from Gregory of Nazianzus’ Oration 29 and Oration 38, the latter delivered on Christmas Day 380 AD.]
Christ is born, glorify Him!
Christ from heaven, go out to meet Him. Christ on earth; be ye exalted. Sing unto the Lord all the whole earth; and that I may join both in one word, Let the heavens rejoice, and let the earth be glad, for Him Who is of heaven and then of earth. Christ in the flesh, rejoice with trembling and with joy; with trembling because of your sins, with joy because of your hope. Christ of a Virgin; O you Matrons live as Virgins, that you may be Mothers of Christ. Who does not worship Him That is from the beginning? Who does not glorify Him That is the Last?
Again the darkness is past; again Light is made; again Egypt is punished with darkness; again Israel is enlightened by a pillar. The people that sat in the darkness of ignorance, let it see the Great Light of full knowledge. Old things are passed away, behold all things have become new. The letter gives way, the Spirit comes to the front. The shadows flee away, the Truth comes in upon them. Melchisedec is concluded. He that was without Mother becomes without Father (without Mother of His former state, without Father of His second). The laws of nature are upset; the world above must be filled. Christ commands it, let us not set ourselves against Him. O clap your hands together all you people, because unto us a Child is born, and a Son given unto us, Whose Government is upon His shoulder (for with the Cross it is raised up), and His Name is called The Angel of the Great Counsel of the Father. Let John cry, Prepare ye the way of the Lord: I too will cry the power of this Day. He Who is not carnal is Incarnate; the Son of God becomes the Son of Man, Jesus Christ the Same yesterday, and today, and for ever.
For God was manifested to man by birth. On the one hand Being, and eternally Being, of the Eternal Being, above cause and word, for there was no word before The Word; and on the other hand for our sakes also Becoming, that He Who gives us our being might also give us our Well-being, or rather might restore us by His Incarnation, when we had by wickedness fallen from wellbeing. The name Theophany is given to it in reference to the Manifestation, and that of Birthday in respect of His Birth. 
He was born—but He had been begotten: He was born of a woman—but she was a Virgin. The first is human, the second Divine. In His Human nature He had no Father, but also in His Divine Nature no Mother. Both these belong to Godhead.
He dwelt in the womb—but He was recognized by the Prophet, himself still in the womb, leaping before the Word, for Whose sake He came into being.
He was wrapped in swaddling clothes—but He took off the swathing bands of the grave by His rising again.
He was laid in a manger—but He was glorified by Angels, and proclaimed by a star, and worshipped by the Magi. Why are you offended by that which is presented to your sight, because you will not look at that which is presented to your mind?
He was driven into exile into Egypt—but He drove away the Egyptian idols.
He had no form nor comeliness in the eyes of the Jews—but to David He is fairer than the children of men. And on the Mountain He was bright as the lightning, and became more luminous than the sun, initiating us into the mystery of the future.
He was baptized as Man—but He remitted sins as God—not because He needed purificatory rites Himself, but that He might sanctify the element of water.
He was tempted as Man, but He conquered as God; yea, He bids us be of good cheer, for He has overcome the world.
He hungered—but He fed thousands; yea, He is the Bread that gives life, and That is of heaven. He thirsted—but He cried, If any man thirst, let him come unto Me and drink. Yea, He promised that fountains should flow from them that believe.
He was wearied, but He is the Rest of them that are weary and heavy laden.
He was heavy with sleep, but He walked lightly over the sea. He rebuked the winds, He made Peter light as he began to sink.
He pays tribute, but it is out of a fish; yea, He is the King of those who demanded it.
He is called a Samaritan and a demoniac;—but He saves him that came down from Jerusalem and fell among thieves; the demons acknowledge Him, and He drives out demons and sinks in the sea legions of foul spirits, and sees the Prince of the demons falling like lightning.
He is stoned, but is not taken.
He prays, but He hears prayer.
He weeps, but He causes tears to cease.
He asks where Lazarus was laid, for He was Man; but He raises Lazarus, for He was God.
He is sold, and very cheap, for it is only for thirty pieces of silver; but He redeems the world, and that at a great price, for the Price was His own blood.
As a sheep He is led to the slaughter, but He is the Shepherd of Israel, and now of the whole world also.
As a Lamb He is silent, yet He is the Word, and is proclaimed by the Voice of one crying in the wilderness.
He is bruised and wounded, but He heals every disease and every infirmity.
He is lifted up and nailed to the Tree, but by the Tree of Life He restores us; yea, He saves even the Robber crucified with Him; yea, He wrapped the visible world in darkness.
He is given vinegar to drink mingled with gall. Who? He who turned the water into wine, who is the destroyer of the bitter taste, who is Sweetness and altogether desire.
He lays down His life, but He has power to take it again; and the veil is rent, for the mysterious doors of Heaven are opened; the rocks are cleft, the dead arise.
He dies, but He gives life, and by His death destroys death.
He is buried, but He rises again;
He goes down into Hell, but He brings up the souls;
He ascends to Heaven, and shall come again to judge the quick and the dead….
This is our present Festival; it is this which we are celebrating today, the Coming of God to Man, that we might go forth, or rather (for this is the more proper expression) that we might go back to God—that putting off the old man, we might put on the New; and that as we died in Adam, so we might live in Christ, being born with Christ and crucified with Him and buried with Him and rising with Him. For I must undergo the beautiful conversion, and as the painful succeeded the more blissful, so must the more blissful come out of the painful. For where sin abounded Grace did much more abound; and if a taste condemned us, how much more does the Passion of Christ justify us? Therefore let us keep the Feast, not after the manner of a heathen festival, but after a godly sort; not after the way of the world, but in a fashion above the world; not as our own but as belonging to Him Who is ours, or rather as our Master’s; not as of weakness, but as of healing; not as of creation, but of re-creation.