All Hail, Adorèd Trinity

All hail, adorèd Trinity;
All hail, eternal Unity;
O God the Father, God the Son,
And God the Spirit, ever One.

Behold to Thee, this festal day,
We meekly pour our thankful lay;
O let our work accepted be,
That sweetest work of praising Thee.

Three Persons praise we evermore,
One only God our hearts adore;
In Thy sure mercy ever kind
May we our true protection find.

O Trinity! O Unity!
Be present as we worship Thee;
And with the songs that angels sing
Unite the hymns of praise we bring.

Author: Unknown

Year: 11

This is an anonymous Latin hymn ("O lux beata Trinitas") traditionally dated to the 11th century or earlier; the English translation given here is usually attributed to John Mason Neale (1850s), but the original words/lyrics are medieval and of unknown authorship.