Kantate, BWV 26 "Ach wie flüchtig, ach wie nichtig"

Ach wie flüchtig, ach wie nichtig (Ah, how fleeting, ah how insignificant), BWV 26, is a church cantata by Johann Sebastian Bach. He composed the chorale cantata in Leipzig for the 24th Sunday after Trinity and first performed it on 19 November 1724.

The cantata is based upon the hymn "Ach wie flüchtig, ach wie nichtig", versed and composed by Michael Franck in 1652. The tune was later edited by Johann Crüger. It is the only time Bach used this hymn, except BWV 644 (Orgelbüchlein). Its theme, the transience of human life, is the only connection to the prescribed gospel reading. The first and last stanza are used unchanged in both text and tune: the former is treated as a chorale fantasia, the latter as a four-part closing chorale. An unknown librettist paraphrased the inner stanzas as arias and recitatives. Bach scored the cantata for four vocal soloists, a four-part choir, and a Baroque instrumental ensemble of horn, flute, three oboes, strings and continuo.