Bach's B minor Mass is among the greatest and most ambitious works of all time. The various stages of composition of the Mass occupied the composer for over two decades: beginning with the Sanctus (1724), by way of the "Missa" of 1733, to the remaining movements of the Ordinary, which were composed during his last years. Thus the Mass, in its wealth of forms with arias, duets, as well as concertante and fugal choruses, displays the essence of Bach's skill and personal style. The "greatest musical work of art of all times and all peoples" (to quote the enthusiastic Hans Georg Nägeli, who first edited the Mass in 1818).