"Helios: Eadweard Muybridge in a Time of Change" explores the groundbreaking work of Eadweard Muybridge, an English immigrant to the U.S. who revolutionized photography. Known for pioneering motion capture, Muybridge achieved a breakthrough by photographing Leland Stanford's horse, Occident, in 1872, proving that all four hooves could be off the ground simultaneously. This work led to the development of the motion picture. The book accompanies a Corcoran Gallery of Art exhibition, featuring essays by scholars discussing Muybridge's influence during a transformative period in American and European history. It traces his journey from bookseller to renowned photographer, operating as Helios.