Direct biblical statement
Luke 1:35
The Holy Spirit will overshadow thee
35 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.
Douay–Rheims · Challoner revision · Luke 1:35
Why this matters
The angel attributes Jesus’ conception to the Holy Spirit and the power of the Most High. The language of overshadowing invites comparison with the sanctuary cloud, a traditional Ark typology rather than an explicit identification of Mary as the Ark.