Mozart's Requiem is a work we will never really have. It is among those unfinished works (in this case unfinished because of Mozart's untimely death) that will remain an enigma for all time. One may query what it might have sounded like had Mozart lived to complete it. Mozart had almost completed the Introit and Kyrie and also the vocal parts and bass line for the Sequentia and the Offertorium. What had yet to be fleshed out were the instrumental parts for these last two sections and the composition of the remaining movements of this requiem mass.
Determined that this work should be finished so she would not have to return the commission payment, and after having been turned down by several musicians, Mozart's widow received agreement from Franz Xaver Süssmayr to undertake the daunting task of the Requiem's completion. Süssmayr, who was sometimes employed by Mozart as a composer and collaborator, was a composition student of Mozart's at the time of Mozart's death. After Mozart died, Süssmayr took instruction in vocal music composition from Salieri. (One can query, therefore, whether Salieri may have had a hand in helping Süssmayr complete Mozart's Requiem!)
Armed with various scraps and sketches Mozart had left, Süssmayr did a credible job, which has been the mainstay performing version for almost 200 years. The Süssmayr version, however, is not without its critics. So, in recent times, along with a discovery in the 1960s of Mozart's sketch of a draft for a Rex Tremendae and an Amen fugue, musicologists (including Franz Beyer, Richard Maunder, Duncan Druce, and Robert D. Levin) with varying success, have produced additional editions in an attempt to emend Süssmayr's good intentions. This, a live 2002 recording with Christian Thielemann conducting the Munich Philharmonic and featuring outstanding young vocal soloists, is a fine, large-scale realization of Süssmayr's completion and very well performed. It is a precise and clear reading, bold, driving, and straight-forward, not ethereal, plaintive, and contemplative, and one of the best of the Süssmayr edition.