Mozart Requiem Introitus & Kyrie

From the manuscript of the Requiem, in Mozart's hand

     While it's not strictly speaking a Lenten composition, Mozart's Requiem Mass, which he was still composing at the time of his death, powerfully lends itself to the penitential nature of the liturgical season. 
     For more than two centuries a lively debate has gone on, and continues today, concerning who composed what parts of the Requiem and the somewhat murky circumstances of its commissioning and completion.  Notwithstanding the controversies both scholarly and fanciful (as in, for instance, the play and film Amadeus), Mozart's final work is a magnificent and moving composition.  
    The clip below, from a performance in St. Stephen's Cathedral in Vienna conducted by Sir Georg Solti, includes the Introit and the Kyrie.  When Mozart died he had finished the Introit; we have the composer's own notation for the vocal parts and portions of the orchestration for the Kyrie, which seems to have been put into its finished form by the composer's student Franz Joseph Süssmayr.