Drop down you heavens from above, and let the skies pour down righteousness; let the earth open, and let it bring forth salvation.
During Advent, those who use The Prayer Book Office (an expansion of the 1979 Book of Common Prayer's Rite II daily prayer services) by the late Howard Galley will be familiar with this antiphon said before and after the Song of Mary (or Magnificat, from the Gospel according to Luke). Like all antiphons, it sharpens the sense of a biblical text according to the time of year or the particular feast day/commemoration being observed.
This particular antiphon, drawn from the Prophets, is cast in the form of a plea to God -- a plea for righteousness and salvation. The image is that these things will come to us both from heaven and earth. This is, in fact, accomplished in the Song of Mary which the antiphon frames. The righteousness of God is poured into the world through the "overshadowing of the Holy Spirit" at the Annunciation, and salvation wells up into humanity through the Incarnation of God in Christ, made possible equally by the gift of human flesh through the Virgin Mary. In the Nativity, this plea to God is brought to fruition, the "fruit" of the Blessed Virgin's womb St. Elizabeth exalts at the time of the Visitation (when the Magnificat was first uttered by St. Mary).
As with so much of the Catholic and liturgical path in Christianity, we have here a rich and complex meditation on great mysteries of the Faith put forth with splendid economy and using the simplest imagery. It is yet another reason to rejoice in the gift of our Anglican heritage, to practice that heritage that we might be formed into better disciples of Christ through it, and to call on the Church's leadership to make that heritage better-known in its common life.