Primo die quo Trinitas

(Found here)

This day the blessed Trinity

    The universe began;

This day the world’s Creator rose.

    O’ercoming death for man.

Casting betimes dull sloth away,

    We too will rise by night;

And with the Prophet seek the Lord,

    Before the dawning light.

So may He stretch his hand to save,

    And hear us in his love;

And, cleans’d from guilt, our souls restore

    To their blest home above.

So, while on this his holy Day,

    At this most sacred hour,

Our psalms amid the stillness rise,

    May He his blessings shower.

Father of lights! keep us this day

    From sinful passions free;

Grant us, in every word, and deed,

    And thought, to honour Thee.

Thou Lord of chastity divine!

    Grant us the grace to quell

Those flames impure, which, cherish’d here,

    Increase the flames of hell.

Saviour, of thy sweet clemency,

    Wash Thou our sins away;

Grant us thy peace—grant us with Thee

    The joys of endless day.

Father of mercies! hear our cry;

    Hear us, coequal Son;

Who reignest with the Holy Ghost,

    While ceaseless ages run.

~St. Gregory the Great (560-604) – from Lyra Catholica