The frightfully successful collection of balances in this 40th cantata, Darzu ist erschienen der Sohn Gottes ("For this purpose the Son of God was made visible') was premiered 26 December1723 in Leipzig. It features a unique distribution of movements that strike a compelling balance: chorus, recitative, chorale (chorus), aria, recitative, chorale (chorus), aria, and chorale. This sort of inverted palindrome breaks from a more conventional style of two recitative and aria pairs, each begun with a chorus, with the work concluded by a final chorale. Part of the reason Bach's legacy is so enduring is his ability to make music simple more interesting, the form more compelling, such as is heard here. The instrumentation continually varies, as does the range of the singer taking on the next solo section. Everything keeps changing, yet affirming the basic material of this single, cohesive work. The opening chorus draws text from I John 3: 8, but it is not known who wrote the poetry. In tone and in musical treatment, this cantata is an aggressive denunciation of the devil. In the first chorus horn, oboes, strings and continuo perform a ritornello that accompanies the chorus' announcement that the destruction of Satan and his works is at hand. This is a martial statement, and there is an implicit challenge in the general atmosphere of the cantata. Later in the bass' aria, the downfall of Satan is further elaborated on with text drawn from Genesis 3: 15, wherein the dark angel is portrayed as a snake. Other references to the bible then go on to compare Jesus to hen protecting her chicks (Matt. 23: 34-9) and other, comparatively pleasant metaphors. Some work painting exists as well, as is heard in the tenor aria with the word erschrecken (‘terrible'), which is heard as an extended melisma to suggest the breathlessness of fear. In all, there is an incredible wealth of musical beauty to comment on in the 40th cantata. Readers would do well to make a first hand investigation. ~ John Keillor, All Music Guide
