The voice of the Holy Ghost?
According to German theological tradition, which Bach knew very well, the alto voice was the very symbol of that of the Holy Ghost. These three solo cantatas do not contradict the rule, although we do not always know for whom Bach wrote them: it was neither a woman nor a castrato, so it could only be a falsetto or an extremely accomplished boy. These works demand enormous vocal virtuosity. Their extraordinary musical variety embraces sublime consolatory lullabies, a faithful echo of an organ concerto (BWV 170), and the dramatic qualities of an oratorio.