Hark! the Herald Angels Sing. The words to this traditional Christmas hymn were written by Charles Wesley and first appeared in 1739 in Hymns and Sacred Poems.
In 1840 Felix Mendelssohn was commissioned to create a cantata to celebrate the quarter centenary of the invitation of movable type printing, by Johanes Gutenburg. An excellent moment in time to celebrate to my reader/author mind. It's quite a stirring piece, I guess. :)
Finally English musician William H. Cummings adapted the music to fit the lyrics we know so well.
Here's part of the original cantata