Eternal God, Thou King of kings,
Who reignest one, Thou one in three,
From age to age eternally.
TU TRINITATIS UNITAS
Attributed by some, but with a small degree of probability, to Gregory the Great. The hymn occurs in all the editions of the Roman Breviary, as also in the Sarum, York, and Aberdeen Breviaries.
I
O Thou Eternal One in Three,
Dread Ruler of the earth and sky,
Accept the praise we yield to Thee,
Who, waking, lift our songs on high.