While Jean-Philippe Rameau left behind copious evidence of his changing beliefs as a music theorist, he remained silent about his most deeply held beliefs as a composer of opera. His occasional protestations of admiration for Lully, and his petulant responses to criticism, have formed a small basis for the large amount of commentary on his compositional career. The possibility remains, however, that Rameau's theoretical writings could offer some clues about his compositions and, more generally, about his career as a composer. I am thinking of a brief, but well-known moment in his career when theoretical remarks and compositional attitudes worked together in the performance of what we today would consider an analytical act: his commentary on Lolly's monologue, ‘Enfin it est en ma puissance’, from Act II scene 5 of Armide .Rameau published this commentary in 1754 in his Observations sur notre instinct pour la musique , as a response to Rousseau's criticism of Lolly's monologue in the Lettre sur la musique française of 1753. The commentary is well known in modern scholarship and has been the subject of a number of studies, the most thorough being Cynthia Verba's work on the evolution of implied chromaticism in Rameau's theories. Here we will be concerned less with its purely theoretical content than with how Rameau's discourse can be said to betray his compositional beliefs about setting texts to music.