Cantata BWV 36 has a complicated history. It began life in 1727 as a secular cantata. By 1731 there had been as many as four versions of the work, all of them for specific celebratory secular occasions In 1731 Bach added all of the chorale-based movements and adapted the text to fit the first Sunday in Advent. It is a tribute to the consistency and purity of his style that the work achieved a unity one would never expect from such a history. The joyous opening chorus has a wonderful leaping quality to its vocal lines that set the piece out on a wonderful journey. The first sacred insert is a detailed and sober duet based upon the great Advent Chorale, "Nun komm, der Heiden Heiland." After a melancholy tenor aria a simple four-voice version of "Wie schön leuchtet der Morgenstern" ends the first half of the cantata. The warm and lovely bass aria that begins the second half of the cantata recaptures the glow of the opening chorus. Another chorale insertion, this time an energetic trio sonata with the two Oboes d'amore and tenors leads us into the climax of both the secular and sacred versions of the work, the enchanting aria for muted violin and soprano. No work of Bach ever illustrated more hauntingly a state of grace. The fact that it began life as a secular aria in no way distracts from its holy fire. Another four-voice setting of "Nun komm, der Heiden Heiland" ends the cantata.