At the time of Mozart's death on 5 December 1791 he had only completed the opening movement (Requiem aeternam) in all of the orchestral and vocal parts. The following Kyrie (a double fugue), and most of the Sequence (from Dies Irae to Confutatis), is complete only in the vocal parts and the continuo (the figured organ bass), though occasionally some of the prominent orchestral parts have been...