His Heilig Wq 217 is just 6 minutes long. Bach, however, put all his art into these few minutes, as he himself wrote to his publisher: „ Here I have proved the most daring and hard work ... It will be my swan song of this nature, and serve to ensure that you do not forget myself too soon after my death“. The work requires an extraordinary instrumentation: two full orchestras with 3 Trumpets, 2 Oboes and Strings and two mixed choirs. A sensitive alto solo initiates the work and prepares the dialogue between the choirs of angels and of peoples. It is a musical highlight, when the angel choir modulates from F minor via the tritone interval to B major, initiating the tutti fortissimo. A strong fourpart fugue concludes the short work .