Today is the fourth day of the “O” antiphons, and the Promised One is invoked as the Key of David.
David was the Supreme King, the one who ruled the combined kingdoms of Judah and Israel. From him descended a long line of kings, among them the faithful Hezekiah who ruled in the 8th century BC. Hezekiah had a prime minister called Eliakim, announced by the prophet Isaiah: “On that day I will summon my servant Eliakim. I will place the key of the House of David upon his shoulder. When he opens, no one shall shut. When he shuts, no one shall open” (Isaiah 22, 20-22)
A key is an instrument of power, by which one can open or close, give or withhold. Eliakim was given great power, but the office was too much for him, as it was for all the others who went before him. So the people were left to wait for the Promised One, who alone would be equal to the office, to come and free his people, to lead them from the darkness of their captivity into the light of God’s life.
“O Key of David, scepter of the house of Israel, who opens and no one can close, who closes and no one can open, come and save the captives who live in darkness and in the shadow of death”. (Liturgy of Evening Prayer December 20)