Grates nunc omnes

Grates nunc omnes is the title and first three words of the Latin sequence for Midnight Mass at Christmas.

History
It dates from the 11th century and first appears in a troparion from Regensburg dating to 1030. It belongs to a set of sequences which fell out of use in the official Roman Catholic liturgy after the Council of Trent.

The Grates nunc omnes sequence was also used for communion and as a processional song. In the 14th century a custom developed of linking sequences with German-language responsorial stanzas. The leise Lovet sistu Ihesu Crist is first documented in a Middle Low German manuscript of 1380 from the Cistercian monastery at Medingen. Martin Luther used this and six more verses to create his Christmas hymn Gelobet seist du, Jesu Christ (EG 23, GL 252).