Conceived By the Holy Spirit
From the Catechism of the Catholic Church, Simplified
Mary Conceives By the Spirit (484-486)
The Annunciation begins "the fullness of time" (Gal 4:4). Mary conceived Jesus in whom the "whole fullness of deity" dwells "bodily." (Col 2:9) To Mary's question, "How can this be, since I do not know man?" the angel replied, "The Holy Spirit will come upon you" (Lk 1:34-35). By the Spirit, Mary conceived the eternal Son of the Father in a humanity drawn from her own.
This Son of the Father is the Christ, anointed by the Spirit from the beginning. This anointing was progressively revealed because his whole life manifested how "God anointed Jesus of Nazareth with the Holy Spirit and with power" (Acts 10:38).