Understanding a Birth

Fratres, humani sensus non est virginei partus aperire mysterium: quod natura non habet, auctoris est, non naturae: est opus superni spiritus, quod sentire non potest caro: ubi non est humanitatis indicium, ibi deitatis est signum, dicente propheta: Ipse Dominus Deus dabit signum. Ecce virgo in utero accipiet. Ubi nil est terreni usus, est ibi coelestis ordinis totum: quod de mundo non est, mundano intellectui non potest subjacere. Conceptus qui virginem servat, partus virginem qui relinquit, divinum est quod generat, non humanum; Deus graditur, ubi vestigum nullatenus humani transitus invenitur; consuetudo deficit, miracula cum geruntur: consuetudines non respiciunt signa, singularitas non admittit exemplum. Sanctus Petrus Chrysologus, Sermo CLIII

Brothers, it is not for the human mind to elucidate the mystery of the virgin birth, because that nature it does not have, it is an act of the Creator not of nature, it is a work of the heavenly Spirit which flesh is not able to know. Where there is no declaration of humanity, there is a sign of the Deity. As the Prophet says, 'God Himself shall give a sign. Behold, a virgin shall conceive in her womb.' 1 Where there is no earthly operation, there is the method of heaven, because it is not of the world, it is not subject to the mundane intellect. He who protected the virgin was conceived, He who was born left her a virgin, a thing Divine happened not something human, God walks where no trace of human passage is to be found, that which is normal perishes when a miracle is made, wondrous signs do not indicate what is customary, unique events do not admit of examples. Saint Peter Chrysologus, Sermon 153 1. Is 7.14