Words From "Munster Gesangbuch," 1677
Music Arranged by Richard S. Willis, (1819-1900) in 1850
The hymn Fairest Lord Jesus has a somewhat elusive history. It is thought to have originated as early as 1607, possibly written by German Jesuits, and called Schnaster Herr Jesu. It first appeared in print in 1677, in a German Roman Catholic publication, but with author unknown. The first three stanzas were translated into English by an unknown. The fourth stanza was added in English by Lutheran pastor and theologian, Joseph A. Seiss in 1873.

Originally this song was most likely sung to a Gregorian Chant by the Jesuit monks. The music for this hymn that was most popular with 17th Century German peasants was a tune from an ancient Silesian folk song. In 1850, Richard S. Willis, composer of the music for It Came upon a Midnight Clear, arranged the folk song for use in church hymnals.

http://www.faithclipart.com/guide/Christian-Music/hymns-the-songs-and-the-stories/fairest-lord-jesus-the-song-and-the-story.html
http://www.preparingforeternity.org/hymn_stories/glory_to_his.shtml

Hymns of Glorious Praise, Springfield, Missouri:  Gospel Publishing House, 1969.

Translated from German to English by Joseph A. Seiss (1823-1904) in 1873.

Richard S. Willis, (1819-1900)
Lyrics: Fairest Lord Jesus  

1. Fairest Lord Jesus, Ruler of all nature,
O Thou of God and man the Son,
Thee will I cherish, Thee will I honor,
Thou, my soul's glory, joy and crown.

2. Fair are the meadows, fairer still the woodlands,
Robed in the blooming garb of spring;
Jesus is fairer, Jesus is purer,
Who makes the woeful heart to sing.

3. Fair is the sunshine, fairer still the moonlight,
And all the twinkling starry host;
Jesus shines brighter, Jesus shines purer
Than all the angels heaven can boast.