What is a lighthouse? What does it mean? What does it do? This book shows how exchanging knowledge across disciplinary boundaries can transform our thinking. Adopting an unconventional structure, this book involves the reader in a multivocal conversation between scholars, poets and artists. Seen through their individual perspectives, lighthouses appear as signals of safety, beacons of enlightenment, phallic territorial markers, and memorials of historical relationships with the sea. However, the interdisciplinary conversation also reveals underlying and sometimes unexpected connections. It elucidates the human and non-human evolutionary adaptations that use light for signalling and warning; the visual languages created by regularity and synchronicity in pulses of light; how lighthouses have generated a whole ‘family’ of related material objects and technologies; and the way that light flows between social and material worlds.