Studies of eighteenth-century French musical aesthetics have traditionally focused on questions of taste treated in the critical literature of the day. During the first half of the century, however, certain French writers were dealing with aesthetics in the stricter sense of the word, proposing theories of beauty that suited existing philosophical values. The treatises in which these ideas were set forth--Jean-Pierre de Crousaz' Traité du beau, Jean-Baptiste DuBos' Réflexions critiques sur la poësie et sur la peinture, Yves-Marie André's Essai sur le beau, and Charles Batteux' Les Beaux arts réduits à un même principe--are among the first learned writings to present the musical experience in something other than a mathematical or pedagogical light. This study investigates not only the role music played in these theories of beauty, but also the methodological problems inherent in translating this data into historical information.