Gregory of Nyssa
Catena Aurea · Lukasevangelium 1
Then said Mary unto the angel, How shall this be, seeing I know not a man? And the angel answered and said unto her, The Holy Ghost shall come upon thee, and the power of the Highest shall overshadow thee: therefore also that holy thing which shall be born of thee shall be called the Son of God.
(in Diem Natal.) Moreover, the power of the Highest shall overshadow thee. Christ is the power of the most high King, who by the coming of the Holy Spirit is formed in the Virgin.