Epiphany Lauds

This hymn is in the Cyberhymnal, here. Here's the description there:

Un­known au­thor, writ­ten be­tween the 10th and 13th Cen­tu­ries (A Pa­tre Un­i­gen­i­tus); trans­lat­ed from La­tin to Eng­lish by John M. Neale, St. Mar­ga­ret’s Hymn­al, 1875, alt.

The tune they link on that page, De­us Tu­or­um Mil­i­tum, from the Gre­no­ble An­ti­phon­er, 1753, is one of my favorites; it's the same hymn tune used for "O Love, How Deep, How Broad, How High."

But it's not the tune given above; I don't know where it came from, or even what it sounds like. Will continue to look for it on the web.