Jean Millet's L Art de bien chanter (1666), describes the air de cour and its ornamentation as it existed in France during the first half of the seventeenth century. This work, translated for the first time into English and transcribed into modern notation, and B6nigne de Bacilly's Remarques curieuses sur l'art de bien chanter (1668) are the only detailed treatises explaining vocal ornamentation during this period. To clarify his ornamentation method, Millet introduces terms referring to placement of agrements, though few performers used them. Millet expresses the old style, popular under Louis XIII, and the provincial view. Bacilly's treatise deals with the air de cour under Louis XIV, which had a more Italian flavor. He gives aesthetic principles aiding the performer in placing and selecting ornaments. Though Millet and Bacilly describe the same practice, striking differences exist between the two air de cour styles.