The angel says to Mary: “The power of the Most High will cover you with its shadow.” It ‘a reminder of the holy cloud that during the Exodus journey, stopped over the Tent of meeting, the ark of the covenant, which the people of Israel brought with them, and that indicated the presence of God (cf. Ex 40 ,40,34-38). Mary is the new holy tabernacle, the new Ark of the Covenant: with her “yes” to the words of the Archangel, God receives a home in this world, He whom the universe can not contain comes to dwell in the womb of a virgin.

–Pope Benedict XVI, from his Audience this past week on the origins of Jesus.