The autograph manuscript (acquired by the Austrian National Library in 1831–1838) shows the finished and orchestratedIntroit in Mozart’s hand, as well as detailed drafts of the Kyrie and the sequenceDies Irae as far as the first eight bars of the “Lacrymosa” movement, and the Offertory. It cannot be shown to what extent Süssmayr may have depended on now lost “scraps of paper” for the remainder; he later claimed the Sanctus and Agnus Dei as his own. Walsegg probably intended to pass the Requiem off as his own composition, as he is known to have done with other works. This plan was frustrated by a public benefit performance for Mozart’s widow Constanze. A modern contribution to the mythology is Peter Shaffer‘s 1979 play Amadeus, in which a mysterious messenger orders Mozart to write a requiem mass, giving no explanation for the order; Mozart (in the play) then comes to believe that the piece is meant to be the requiem mass for his own funeral.