Maternity of the Blessed Virgin Mary

"His Mother was chosen a Virgin of the kingly lineage of David, and when she was to grow heavy with the sacred Child, her soul had already conceived him before her body.  She learned the counsel of God announced to her by the Angel, lest the unwonted events should alarm her.  The future Mother of God knew what was to be wrought in her by the Holy Ghost, and that her modesty was absolutely safe.  For why should she, unto whom was promised all sufficient strength through the power of the Highest, have felt hopeless merely because of the unexampled character of such a conception?  She believeth, and her belief is confirmed by the attestation of a miracle which hath already been wrought.  The fruitfulness of Elizabeth, before unhoped for, is brought forward that she might not doubt that he who had given conception unto her that was barren, would give the same unto her that was Virgin.  And so the Word of God, the Son of God, who was in the beginning with God, by whom all things were made, and without whom was not anything made that was made, to deliver man from eternal death, was made man.

Our Lord Jesus Christ, descending from his throne in heaven, but leaving not that glory which he hath with the Father, cometh into this lower world by being born after a new order and in a new birth.  He cometh after a new order, in that he who is unseen among his own, was seen among us; the Incomprehensible was fain to be comprehended, and he that is from everlasting to everlasting began to be in time.  He was the Offspring of a new birth; conceived of a maiden, without the passion of any fleshly father, without any breach of his Mother's virginity, since such a birth beseemed the coming Saviour of mankind, who was to have in him the nature of man's being, and to be free of any defilement of man's flesh.  Though he sprung not as we spring, yet is his nature as our nature; we believe that he is free from the use and custom of men; but it was the power of God which wrought that a maiden should conceive, that a maiden should bring forth, and yet abide a maiden still."

-- From a sermon by St Leo the Great

** This feast is observed by all following the 1962 traditional liturgical calendar