And in the sixth month, the angel Gabriel was sent from God into a city of Galilee, called Nazareth,  To a virgin espoused to a man whose name was Joseph, of the house of David; and the virgin’s name was Mary.  And the angel being come in, said unto her: Hail, full of grace, the Lord is with thee: blessed art thou among women.  Who having heard, was troubled at his saying, and thought with herself what manner of salutation this should be.  And the angel said to her: 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 for ever.  And of his kingdom there shall be no end.  And Mary said to the angel: How shall this be done, because I know not man?  And the angel answering, said to her: 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.
Luke 1: 26-35