The “O” Antiphons are the verses for the ancient hymn O Come Emmanuel. The first letter of the Messianic titles: Emmanuel, Rex, Oriens, Clavis, Radix, Adonai, Sapienta—spell out Latin words ERO CRAS, meaning, “Tomorrow, I will come.”
O Sapienta (December 17)
O Wisdom (Eccl 24: 5), you came forth from the mouth of the Most High (Sir 24: 30), and reach-ing from beginning to end, you ordered all things mightily and sweetly (Wis 8: 1). Come, and teach us the way of prudence (Isa 40: 14).
O Adonai (December 18)
O Adonai or O Lord and Ruler (Exod 6: 13) and Ruler of the house of Israel (Mat 2: 6), you appeared to Moses in the fire of the burning bush (Exod 3: 2), and on Mount Sinai gave your Law (Exod 20). Come and with outstretched arm re-deem us (Jer 32: 21).
O Radix Jesse (December 19)
O Root of Jesse, you stand for the ensign of all mankind (Isa 11: 10); before you kings shall keep silence and to you all nations shall have recourse (Isa 52: 15). Come, save us, and do not delay (Hab 2: 3).
O Clavis David (December 20)
O Key of David (Apoc 3: 7) Scepter of the house of Israel, you open and no man closes; you close and no man opens (Isa 22: 22). Come, and deliver him from the chains of prison who sits in darkness and in the shadow of death (Ps 107: 10).
O Rising Dawn (December 21)
(Zac 6: 12), Radiance of the Light eternal (Hab 3: 4) and Sun of Justice (Mal 3: 20); Come, enlighten those who sit in darkness and the shadow of death (Ps 107: 10: Lk 1: 78).
O Rex Gentium (December 22)
O King of the Gentiles (Hag 2: 8), Daesired of all, you are the cornerstone that binds two into one (Eph 2: 20). Come, and save poor man whom you fashion out of clay (Gen 2: 7).
O Emmanuel (December 23)
O Emmanuel (Isa 7: 14; 8: 8), our King and Lawgiver (Gen 49: 10; cf. Ezek 21: 32), the Ex-pected of the nations and their Savior (Isa 33:22: Come, and save us, O Lord our God.