BWV 36 ("Soar joyfully aloft") has a particularly complex history. The version under consideration here represents Bach's reworking of a work that started life in 1725 as a secular cantata of the same name (BWV 36c). Composed to a libretto by the Leipzig civil servant and poet Picander (the pseudonym of the poet Christian Friedrich Henrici), the cantata was written as a birthday tribute to an unidentified Leipzig academic. The following year, Bach revived the work with a new text by Picander for the birthday of the wife of his old employer, Prince Leopold of Anhalt-Cöthen, with whom he maintained close contact after moving to Leipzig. This version, now lost, bears the name Steigt freudig in die Luft, BWV 36a. At some point between this second secular version and 1730, Bach decided to turn the work into a sacred cantata for Advent Sunday, adding a chorale and adapting it to a new text by an unknown author. In 1731, he returned to the work yet again, expanding it from five numbers to eight, while further restructuring and revising the existing numbers. Finally, in 1735, Bach returned the work to its secular origins using yet another new text, Die Freude reget sich (BWV 36b), probably also by Picander. According to the Bach scholar Christoph Wolff the occasion may have been the inauguration of the Leipzig professor Andreas Florens Rivinius as rector of the Thomasschule. The whole history of BWV 36 provides an interesting insight into the working methods of Bach, who, throughout his composing life, constantly reworked and refined material he considered to be of value.
The 1731 sacred cantata is a large-scale work divided into two parts, the first of which would have been performed before the sermon, the second afterwards.
The scoring of the cantata is the usual SATB vocal disposition, with solo arias for soprano, tenor, and bass; the instrumental forces are a pair of oboes d'amores, strings, and continuo. A particular feature of the 1731 version was the addition of three stanzas of Martin Luther's great Advent hymn "Nun komm der Heiden Heiland" (Nos. 2, 4, and 6), previously used in the two Advent cantatas which bear its name, BWV 61 and 62. For the final chorale Bach retained a strophe he had added in 1730 from another beautiful Advent hymn, Philip Nicolai's "Wie schön leuchtet der Morgenstern" (1599).
The opening chorus, as befits the season and its original secular celebratory origins, is a joyous affair; each part enters in imitation, but the writing involves both contrapuntal and homophonic passages. The only aria in the first part is for tenor; it is a dance-like movement in da capo form with an obbligato part for oboe d'amore, the text casting Jesus in the familiar role of bridegroom of the enraptured soul. Part two opens with a spirited aria for bass ("Welcome precious treasure"), the text calling on Jesus to enter the "pure heart." The final soprano aria is a delicately textured movement with muted string accompaniment.