He is a true and devout worshipper, dearly-beloved, of to-day's festival who thinks nothing that is either false about the Lord's Incarnation or unworthy about His Godhead. For it is an equally dangerous evil to deny in Him the reality of our nature and the equality with the Father in glory. When, therefore, we attempt to understand the mystery of Christ's nativity, wherein He was born of the Virgin-mother, let all the clouds of earthly reasonings be driven far away and the smoke of worldly wisdom be purged from the eyes of illuminated faith: for the authority on which we trust is divine, the teaching which we follow is divine. Inasmuch as whether it be the testimony of the Law, or the oracles of the prophets, or the trumpet of the gospel to which we apply our inward ear, that is true which the blessed John full of the Holy Spirit uttered with his voice of thunder(1) : "in the beginning was the Word: and the Word was with God, and the Word was God. The same was in the beginning with God. All things were made through Him, and without Him was nothing made(2) ." And similarly is it true what the same preacher added: "the Word became flesh and dwelt in us: and we beheld His glory, the glory as of the only-begotten of the Father(3) ." Therefore in both natures it is the same Son of God taking what is ours and not losing what is His own; renewing man in His manhood, but enduring unchangeable in Himself. For the Godhead which is His in common with the Father un lerwent no loss of omnipotence, nor did the "form of a slave" do despite to the "form of God," because the supreme and eternal Essence, which lowered Itself for the salvation of mankind, transferred us into Its glory, but did not cease to be what It was. And hence when the Only-begotten of God confesses Himself less than the Father(4) , and yet calls Himself equal with Him(5) , He demonstrates the reality of both forms in Himself: so thai the inequality proves the human nature, and the equality the Divine.
The bodily Nativity therefore of the Son of God took nothing from and added nothing to His Majesty because His unchangeable substance could be neither diminished nor increased. For that "the Word became flesh" does not signify that the nature of God was changed into flesh, but that the Word took the flesh into the unity of His Person: and therein undoubtedly the whole man was received, with which within the Virgin's womb fecundated by the Holy Spirit, whose virginity was destined never to be lost(6) , the Son of God was so inseparably united that He who was born without time of the Father's essence was Himself in time born of the Virgin's womb. For we could not otherwise be released from the chains of eternal death but by Him becoming humble in our nature, Who remained Almighty in His own. And so our Lord Jesus Christ, being at birth true man though He never ceased to be true God, made in Himself the beginning of a new creation, and in the "form" of His birth started the spiritual life of mankind afresh, that to abolish the taint of our birth according to the flesh there might be a possibility of regeneration without our sinful seed for those of whom it is said, "Who were born not of blood, nor of the will of the flesh, nor of the will of man, but of God(7) ." What mind can grasp this mystery, what tongue can express this gracious act? Sinfulness returns to guiltlessness and the old nature becomes new; strangers receive adoption and outsiders enter upon an inheritance. The ungodly begin to be righteous, the miserly benevolent, the incontinent chaste, the earthly heavenly. And whence comes this change, save by the right hand of the Most High? For the Son of God came to "destroy the works of the devil(8) ,"and has so united Himself with us and us with Him that the descent of God to man's estate became the exaltation of man to God's.
But in this mercifulness of God, dearly beloved, the greatness of which towards us we cannot explain, Christians must be extremely careful lest they be caught again in the devil's wiles and once more entangled in the errors which they have renounced. For the old enemy does not cease to "transform himself into an angel of light(9) ," and spread everywhere the snares of his deceptions, and make every effort to corrupt the faith of believers. He knows whom to ply with the zest of greed, whom to assail with the allurements of the belly, before whom to set the attractions of self-indulgence, in whom to instil the poison of jealousy: he knows whom to overwhelm with grief, whom to cheat with joy, whom to surprise with fear, whom to bewilder with wonderment: there is no one whose habits he does not sift, whose cares he does not winnow, whose affections he does not pry into: and wherever he sees a man most absorbed in occupation, there he seeks opportunity to injure him. Moreover he has many whom he has bound still more tightly because they are suited for his designs, that he may use their abilities and tongues to deceive others. Through them are guaranteed the healing of sicknesses, the prognosticating of future, events, the appeasing of demons and the driving away of apparitions(10) . They also are to be added(11) who falsely allege that the entire condition of human life depends on the influences of the stars, and that that which is really either the divine will or ours rests with the unchangeable fates. And yet, in order to do still greater harm, they promise that they can be changed if supplication is made to those constellations which are adverse. And thus their ungodly fabrications destroy themselves; for if their predictions are not reliable, the fates are not to be feared: if they are, the stars are not to be venerated.
From such a system of teaching proceeds also the ungodly practice of certain foolish folk who worship the sun as it rises at the beginning of daylight from elevated positions: even some Christians think it is so proper to do this that, before entering the blessed Apostle Peter's basilica, which is dedicated to the One Living and true God, when they have mounted the steps which lead to the raised platform(12) , they turn round and bow themselves towards the rising sun and with bent neck do homage to its brilliant orb. We are full of grief and vexation that this should happen, which is partly due to the fault of ignorance and partly to the spirit of heathenism: because although some of them do perhaps worship the Creator of that fair light rather than the Light itself, which is His creature, yet we must abstain even flora the appearance of this observance: for if one who has abandoned the worship of gods, finds it in our own worship, will he not hark back again to this fragment of his old superstition, as if it were allowable, when he sees it to be common both to Christians and to infidels?
This objectionable practice must be given up therefore by the faithful, and the honour due to God alone must not be mixed up with those men's rites who serve their fellow-creatures. For the divine Scripture says: "Thou shalt worship the Lord thy God, and Him only shalt thou serve(13) ." Anti the blessed Job, "a man without complaint," as the Lord says, "and one that eschews every evil(14) ," said, "Have I seen the sun when it shone or the moon walking brightly, and my heart hath rejoiced in secret, and I have kissed my hand: what is my great iniquity and denial against the most High God(15) ?" But what is the sun or what is the moon but elements of visible creation and material light: one of which is of greater brightness and the other of lesser light? For as it is now day time and now night time, so the Creator has constituted divers kinds of luminaries, although even before they were made there had been days without the sun and nights without the moon(16) . But these were fashioned to serve in making man, that he who is an animal endowed with reason might be sure of the distinction of the months, the recurrence of the year, and the variety of the seasons, since through the unequal length of the various periods, and the clear indications given by the changes in its risings, the sun doses the year and the moon renews the months. For on the fourth day, as we read, God said: "Let there be lights in the firmament of the heaven, and let them shine upon the earth, and let them divide between day and night, and let them be for signs and for seasons, and for days and years, and let them be in the firmament of heaven that they may shine upon earth."
Awake, O man, and recognize the dignity of thy nature. Recollect thou wast made in the image of God, which although it was corrupted in Adam, was yet re-fashioned in Christ. Use visible creatures as they should be used, as thou usest earth, sea, sky, air, springs, and rivers: and whatever in them is fair and wondrous, ascribe to the praise and glory of the Maker. Be not subject to that light wherein birds and serpents, beasts and cattle, flies and worms delight. Confine the material light to your bodily senses, and with all your mental powers embrace that "true light which lighteth every man that cometh into this world(17) ," and of which the prophet says, "Come unto Him and be enlightened, and your faces shall not blush(18) ." For if we "are a temple of God, and the Spirit of God dwelleth in(19) " us, what every one of the faithful has in his own heart is more than what he wonders at in heaven. And so, dearly beloved, we do not bid or advise you to despise God's works or to think there is anything opposed to your Faith in what the good God has made good, but to use every kind of creature and the whole furniture of this world reasonably and moderately: for as the Apostle says, "the things which are seen are temporal: but the things which are not seen are eternal(20) ." Hence because we are born for the present and reborn for the future, let us not give ourselves up to temporal goods, but to eternal: and in order that we may behold our hope nearer, let us think on what the Divine Grace has bestowed on our nature on the very occasion when we celebrate the mystery of the Lord's birthday. Let us hear the Apostle, saying: "for ye are dead, and your life is hid with Christ in God. But when Christ, who is your life, shall appear, then shall ye also appear with Him in glory(21) :" who lives and reigns with the Father and the Holy Ghost for ever and ever. Amen.