Salvator noster, dilectissimi, hodie natus est, gaudeamus. neque enim locum fas est ibi esse tristitiae, ubi natalis est vitae; quae consumpto mortalitatis timore, nobis ingerit de promissa aeternitate laetitiam. nemo ab huius alacritatis participatione secernitur, una cunctis laetitiae communis est ratio: quia Dominus noster, peccati mortisque destructor, sicut nullum a reatu liberum reperit, ita liberandis omnibus venit. exsultet sanctus, quia propinquat ad palmam. gaudeat peccator, quia invitatur ad veniam. animetur gentilis, quia vocatur ad vitam. Dei namque Filius secundum plenitudinem temporis, quam divini consilii inscrutabilis altitudo disposuit, reconciliandum auctori suo naturam generis assumpsit humani, ut inventor mortis diabolus, per ipsam quam vicerat vinceretur. in quo conflictu pro nobis inito, magno et mirabili aequitatis iure certatum est: dum omnipotens Dominus cum saevissimo hoste, non in sua maiestate, sed in nostra congreditur humilitate, obiciens ei eandem formam eandemque naturam, mortalitatis quidem nostrae participem, sed peccati totius expertem. alienum quippe ab hac nativitate est, quod de omnibus legitur: “nemo mundus a sorde, nec infans, cuius est unius diei vita super terram” [Job 14.4]. nihil ergo in istam singularem nativitatem de carnis concupiscentia transivit, nihil de peccati lege manavit. virgo regi Davidicae stirpis eligitur, quae sacro gravidanda fetu divinam humanamque prolem prius conciperet mente quam corpore. et ne superni ignara consilii ad inusitatos paveret effectus, quod in ea operandum erat a Spiritu sancto, colloquio discit angelico. nec damnum credit pudoris, Dei genitrix mox futura. cur enim de conceptionis novitate desperet, cui efficientia de Altissimi virtute promittitur? confirmatur credentis fides etiam praeeuntis attestatione miraculi, donaturque Elizabeth inopinata fecunditas; ut qui conceptum dederat sterili, daturus non dubitaretur et virgini.
(Leo I, Serm. 21.1)
Our Saviour, dearly-beloved, was born today: let us be glad. For there is no proper place for sadness, when we keep the birthday of the Life, which destroys the fear of mortality and brings to us the joy of promised eternity. No one is kept from sharing in this happiness. There is for all one common measure of joy, because as our LORD the destroyer of sin and death finds none free from charge, so is He come to free us all. Let the saint exult in that he draws near to victory. Let the sinner be glad in that he is invited to pardon. Let the gentile take courage in that he is called to life. For the Son of GOD in the fulness of time which the inscrutable depth of the Divine counsel has determined, has taken on him the nature of man, thereby to reconcile it to its Author: in order that the inventor of death, the devil, might be conquered through that (nature) which he had conquered. And in this conflict undertaken for us, the fight was fought on great and wondrous principles of fairness; for the Almighty LORD enters the lists with His savage foe not in His own majesty but in our humility, opposing him with the same form and the same nature, which shares indeed our mortality, though it is free from all sin. Truly foreign to this nativity is that which we read of all others, “no one is clean from stain, not even the infant who has lived but one day upon earth.” Nothing therefore of the lust of the flesh has passed into that peerless nativity, nothing of the law of sin has entered. A royal Virgin of the stem of David is chosen, to be impregnated with the sacred seed and to conceive the Divinely-human offspring in mind first and then in body. And lest in ignorance of the heavenly counsel she should tremble at so strange a result, she learns from converse with the angel that what is to be wrought in her is of the Holy Ghost. Nor does she believe it loss of honour that she is soon to be the Mother of God. For why should she be in despair over the novelty of such conception, to whom the power of the most High has promised to effect it. Her implicit faith is confirmed also by the attestation of a precursory miracle, and Elizabeth receives unexpected fertility: in order that there might be no doubt that He who had given conception to the barren, would give it even to a virgin. (tr. Philip Schaff)