Restless Passions aims to provide a cultural framework for the instrumental music of Haydn, Mozart, and other composers active during the Age of Sensibility (ca. 1750–1800). During this period in European culture the sensations of the body became the source of intense debate, spurred by scientific inquires into the function of the nervous system. At the same time, the elevated status of the senses challenged traditional conceptions of the soul and its location within the body. The highly charged meeting point between the “nervous” body and the “sensitive” soul gave new meaning to instrumental sound, a medium of sonic changeability requiring extreme sensitivity in acts of performance and reception. As a result, eighteenth-century genres such as fantasias, sonatas, string quartets, and symphonies provide a fascinating window into the way that “change” at the most nuanced level of musical expression reveals broader concerns in 18th-century Europe about the nature of human perception, pleasure, morality, health, identity, and emotion.