The word Trisagion literally means “thrice-holy” in Greek, and refers to the prayer, “Holy God, Holy Mighty, Holy Immortal, have mercy on us;” a prayer we use during the Divine Liturgy and as the basis for our personal daily rule of devotion.

When a disastrous earthquake occurred near Constantinople, people immediately gathered in church to pray and entreat God’s mercy. As they did, one pious little boy heard angels singing this above hymn and told the people to pray using those same words. The Thrice-Holy hymn is quite similar to what the Prophet Isaiah wrote when he envisioned angels in heaven continuously singing: “Holy, Holy, Holy is the Lord of Hosts; the whole earth is full of His glory” (Isaiah 6:3). This, too, is a hymn we sing at every liturgy during the Anaphora.