On the isolated island of Staffa, near Iona, Scotland, stands a natural wonder of the world. Fingal's Cave--an extraordinary cathedral-like space, with its sides and roof made of hexagonal balsatic columns and a floor made of the ocean, whose tides create constant musical sounds. It has been been a source of mystery, spiritual insight, and artistic inspiration for centuries. To understand Fingal and his importance to Celtic culture, we must understand the poems of Ossian and ancient Celtic Christianity. The authors describe the history and importance of Fingal's Cave and the poems of Ossian, showing why they influenced such diverse figures as Medelssohn, Jefferson, Napoleon, and Turner. Illustrated.