"Look favorably on your whole Church, that wonderful and sacred mystery"

"O God of unchangeable power and eternal light: Look favorably on your whole Church, that wonderful and sacred mystery; by the effectual working of your providence, carry out in tranquillity the plan of salvation; let the whole world see and know that things which were being cast down are being raised up, and things which had grown old are being made new, and that all things are being brought to their perfection by him through whom all things were made, your Son Jesus Christ our Lord; who lives and reigns with you, in the unity of the Holy Spirit, one God, for ever and ever. Amen" (1976 Book of common prayer, pp. 280 (Good Friday), 291 (Easter Vigil), 515 (Ordination of a Bishop), 528 (Ordination of a Priest), 540 (Ordination of a Deacon)).

     This, according to Hatchett (Commentary on the American prayer book (The Seabury Press, 1980), p. 248), is no. 432 in the 8th-century Gelasian sacramentary.  Cf. p. 82 in the 1894 Clarendon Press edition of that by H. A. Wilson.  In the current Roman missal, it occurs after the seventh reading in the Easter Vigil at least:

"O God of unchanging power and eternal light, look with favour on the wondrous mystery of the whole Church and serenely accomplish the work of human salvation, which you planned from all eternity; may the whole world know and see that what was cast down is raised up, what had become old is made new, and all things are restored to integrity through Christ, just as by him they came into being. Who lives and reigns for ever and ever. Amen."