Frequently credited with the invention of modern dance, Isadora Duncan was a choreographer, dancer, educator, international star, and author of a bestselling autobiography My Life (1927). Her choreography drew most prominently from popular social dance genres, the poses and gestures depicted in classical art, and exercises promoted by the twentieth-century physical culture movement. Her hybrid performance form combined these popular and ancient influences with expressive solo dance, live orchestral music, non-naturalistic stage décor, and inflammatory curtain-call speeches resembling modernist manifestos. In the first decades of the twentieth century, numerous artists and spectators heralded Duncan as a muse of Modernism. Yet for some contemporaries and later commentators, her understanding of dance as the expression of the soul made her seem nostalgic and anti-modern. In fact, her incongruent combination of metaphysical and materialist discourses, along with her contradictory claims of a desire for popularity and hostility toward popular audiences, highlight common tensions in Modernism. Duncan’s performances and her written and embodied manifestos influenced many spheres of twentieth-century art and culture, including Italian Futurism, the Moscow Art Theatre, Greenwich Village Radicalism, and the women’s movement.