“Amen, amen, I say to you, you will see heaven opened and the angels of God ascending and descending on the Son of Man.”
In her liturgy, the Church joins with the angels to adore the thrice-holy God. She invokes their assistance (in the funeral liturgy's In Paradisum deducant te angeli. . .["May the angels lead you into Paradise. . ."]). Moreover, in the "Cherubic Hymn" of the Byzantine Liturgy, she celebrates the memory of certain angels more particularly (St. Michael, St. Gabriel, St. Raphael, and the guardian angels).
-- CCC 335
Art: Tiziano Vecellio, Archangel Gabriel (detail), polyptych of the Resurrection, 1522.