At the Countess Madeleine's château, a rehearsal of Flamand's newly composed sextet is in progress. Olivier and Flamand debate the relative powers of words and music.he theatre director La Roche wakes from a nap, and reminds them both that impresarios and actors are necessary to bring their work to life. Olivier has written a new play for the Countess's birthday the next day, which will be directed by La Roche, with the Count and the famous actress Clairon performing. La Roche, Olivier and Flamand proceed to a rehearsal. The Count, the Countess's brother, teases his sister about her two suitors, Flamand and Olivier, and tells her that her love of music is due in part to the attentions that Flamand pays her. In turn, she tells her brother that his love of words is in keeping with his attraction to the actress Clairon. The Countess admits that she cannot decide which of her suitors she prefers. Clairon arrives, and she and the Count read a scene from Olivier's play, which culminates in a love sonnet. They leave to join La Roche at the rehearsal. Olivier tells the Countess that he means the sonnet for her. Flamand then sets the sonnet to music, while Olivier declares his love for the Countess. Flamand sings them his new composition, accompanying himself on the harpsichord. Olivier feels that Flamand has ruined his poem, while the Countess marvels at the magic synthesis of words and music. Olivier is asked to make cuts to his play and leaves for La Roche's rehearsal. Flamand declares his love for the Countess and poses the question – which does she prefer, poetry or music? She asks him to meet her in the library the next morning at 11, when she will give him her decision. She orders chocolate in the drawing-room. The actors and La Roche return from their rehearsal and the Count declares that he is bewitched by Clairon. Madeleine tells him of her reluctance to choose between her two suitors, and the brother and sister gently tease each other again. Refreshments are served as dancers and two Italian singers entertain the guests. The Count, Countess, Flamand, Olivier, Clairon and La Roche reflect on the respective merits of dance, music and poetry. The discussion is lively, even aggressive on the part of the men. The Countess challenges Flamand and Olivier to write an opera. The Count and Clairon depart for Paris with the theatre company. As evening falls, the Countess returns, having dressed for supper, and learns from the Major-Domo that her brother has gone to Paris with Clairon, leaving her to dine alone. The Major-Domo reminds her that both Olivier and Flamand will meet her in the library in the morning to learn the ending of the opera. Alone, and still undecided as to both the ending of the opera and her choice of lover, she sings of the inseparability of words and music. In like manner she tells herself that if she chooses one she will win him but lose the other. She consults her image in the mirror, asking "Is there any ending that isn't trivial?" The Major-Domo announces that "Dinner is served" and the Countess slowly leaves the room.