La clemenza di Tito is an Opera Seria in two acts, with an italian libretto by Caterino Mazzolà, after Metastasio. For the premiere, on september 6th 1791 (the day of the coronation of Leopold II, for which the work was comissioned), the role of Sesto was taken by an excellent castrato soprano, Bedini. It was not a success, but on the 30th september, in Prague, it was warmly welcomed. The problem with La Clemenza is not a musical one, Mozart's music is flawless, and deeply touching.. But even for Mazzolà, To change the pompous Mestastasian libretto in three acts, full of the longest recitatives, "and not even a duett" (as Einstein points it) into the schrinked libretto in two acts Mozart set into music, was quite a feat, perhaps too great a feat...