The fact of the Annunciation of the Blessed Virgin Mary is related in Luke, i 26-38. The Evangelist tells us that in the sixth month after the conception of St. John the Baptist by Elizabeth, the angel Gabriel was sent from God to the Virgin Mary, at Nazareth, a small town in the mountains of Galilee. Mary was of the house of David, and was espoused (i. e. married) to Joseph, of the same royal family. She had, however, not yet entered the household of her spouse, but was still in her mother's house, working, perhaps, over her dowry. (Bardenhewer, Maria Verk., 69). And the angel having taken the figure and the form of man, came into the house and said to her: "Hail, full of grace (to whom is given grace, favoured one), the Lord is with thee." Mary having heard the greeting words did not speak; she was troubled in spirit, since she knew not the angel, nor the cause of his coming, nor the meaning of the salutation. And the angel continued and said: "Fear not, Mary, for thou hast found grace with God. Behold thou shalt conceive in thy womb, and shalt bring forth a son; and thou shalt call his name Jesus. He shall be great, and shall be called the Son of the Most High; and the Lord God shall give unto him the throne of David his father; and he shall reign in the house of Jacob forever. And of his kingdom there shall be no end." The Virgin understood that there was question of the coming Redeemer. But, why should she be elected from amongst women for the splendid dignity of being the mother of the Messiah, having vowed her virginity to God? (St. Augustine). Therefore, not doubting the word of Godlike Zachary, but filled with fear and astonishment, she said: "How shall this be done, because I know not man?"
The angel to remove Mary's anxiety and to assure her that her virginity would be spared, answered: "The Holy Ghost shall come upon thee and the power of the Most High shall overshadow thee. And therefore also the Holy which shall be born of thee shall be called the Son of God."