Oh Taste and See

"Listen to what the angel says: Therefore also that Holy Thing Which is [being begotten -- γεννώμενον] of thee, in other words, that Holy Thing Which is growing within your womb in extraordinary manner, and does not at once exist in completed form. Here the mouth of Nestorius is sealed. For that man said that the Son of God did not take flesh by dwelling in the womb of the Virgin, but that a mere man was born of Mary, and only later was this man "accompanied" by God. Let Nestorius hear, therefore, that that Holy Thing Which is being begotten in the womb is the Son of God." -- Blessed Theophylact, The Holy Gospel according to St. Luke