Mozart's requiem was only partially finished at his untimely death in December 1791. His widow Constanza turned to Mozart's students to complete the work which had been commissioned by Count Walsegg in honor of his late wife. Joseph Eybler made the first attempt but returned the manuscript a short time later - still unfinished. Franz Xaver Sussmayr, another student completed the work in 1792. The work was first performed on January 2, 1793 in Vienna in Sussmayr's version, which remains the most widely performed and recorded completion despite disputes over the extent of Sussmayr's...