This opera, Les Horaces, was composed for Paris by the Viennese (but also Italian) Antonio Salieri, on a libretto written by Guillard in 1786. It perfectly illustrates the difficulty of defining the operatic style that prevailed in Europe at the end of the eighteenth century, when the French « tragédie en musique » had undergone considerable change. The libretto suffered in comparison of Corneille, and Salieri’s music did quite match the rules of the « tragédie en musique ». The failure of Les Horaces has to be analysed both in terms of literary and music criticism. Indeed, the fact that the opera was badly received does not mean that it was ill-composed, and by 1786, Salieri’s musical language had already acquired its own specificity. Examples taken from the score will bring such aspects to the fore, and demonstrate that Les Horaces is a lyric drama.