The melody of "In dulci Jubilo" predates Bach's setting - his version is a sophisticated four-part chorale harmonization of this traditional Christmas carol.
Bach's harmonization of this 14th-century macaronic carol (mixing Latin and German) exemplifies Baroque choral craftsmanship. It features in his chorale collections, showcasing contrapuntal rigor within a joyful Christmas context. The BWV 368 version is among his most performed sacred works.