"by the message of an angel"

Fra Angelico, Museo Diocesano, Cortona, Italy.

"Pour forth, we beseech you, O Lord, your grace into our hearts, that we, to whom the Incarnation of Christ your Son was made known by the message of an Angel, may by his Passion and Cross be brought to the glory of his Resurrection.  Who."

     Collect for the Fourth Sunday of Advent, current Roman Missal, and of course the prayer with which the Angelus concludes.  Bruylants, vol. 2, no. 575 on pp. 156-157 =Corpus orationum no. ___, and thus present (for the Feast of the Annunciation) already as no. 879 in the 8th/9th-century Gelasian sacramentary of Angoulême (Paris, B.N. ms lat. 816).  Cf. CCSL 159C, Liber sacramentorum Engolismensis, ed. Saint-Roche (1987), p. 131:

"Gratiam tuam quaesumus Domine mentibus nostris infunde, ut qui angelo nuntiante Christi filii tui incarnationem cognouimus, per passionem eius [et crucem] ad resurrectionis gloriam perducamur.  Per."