Tarare is a libretto which was written by Beaumarchais for a French public, and was replaced by Axur Rè d'Ormus, an Italian libretto written by Da Ponte for the benefit of spectators in Vienna. The link between the two works was the music composed by A. Salieri for both Paris and Vienna. These two operas are excellent examples of the problems encountered to define the lyrical style in Europe at the end of the 18th century. In 1787, Beaumarchais suggested that the rules of dramatic acting should be modified. In his Memoirs Da Ponte explained that he had achieved a 'free translation' of the text and had then realized a new version in 1788. Two questions can be posed: Is Axur Rè d'Ormus an opera buffa? Although it possesses some characteristic features, Da Ponte left out some elements which are usually part of lyrical tragedy, for instance the prologue or some diversions, or divertissements in French; he however kept other aspects that Salieri knew how to enhance. Is Axur Rè d'Ormus a drama tragicomico, that is to say a hybrid form of melodrama known in Vienna? Just like Tarare, it can be rigorously classified as a contemporary lyrical production and thus triggers a real reflection regarding the exact relationship between the librettist and the composer.