I'm doing a few of Buxtehude's lesser known Choral Preludes on different organs of his period.
There are over 40 surviving chorale settings by Buxtehude, and they constitute the most important contributions to the genre in the 17th century.
Buxtehude's principal contributions to the organ chorale are his 30 short chorale preludes. The chorale preludes are usually four-part cantus firmus settings of one stanza of the chorale; the melody is presented in an elaborately ornamented version in the upper voice, the three lower parts engage in some form of counterpoint (not necessarily imitative). Most of Buxtehude's chorale settings are in this form.
The ornamented cantus firmus in these pieces represents a significant difference between the north German and the south German schools; Johann Pachelbel and his pupils would almost always leave the chorale melody unornamented.
The text and probably also the melody are by Martin Luther.