On the isolated island of Staffa, near Iona in the Inner Hebrides of Scotland, an extraordinary collection of stalactites compressed by the surging water creates not only a cathedral-like space inside a cave but also perpetual sound, as the wind and water ebb and flow. This place is called Fingal's cave - a source of mystery, spiritual insight and artistic inspiration for centuries. Mendelssohn and Turner were fascinated by it. Esoteric philosopher and educationalist Rudolf Steiner thought that Fingal - the chief of the ancient Celts, who preserved their religion and culture against pagan marauders - was the great pre-Christian initiate. The cave looms large in the fragmentary poems of Ossian, collected by the 18th century poet James Macpherson. The poems, subject of controversy even to this day, were a great influence on Enlightenment and Romantic figures as diverse as Thomas Jefferson, Walt Whitman, James Fenimoore Cooper, Dickens and many others. Napolean kept the poems of Ossian with him during his Russian campaign. He even commissioned paintings depicting scenes from the poetry and hung them at his country retreat outside Paris. This work explores the meaning of Fingal's initiation rite, the development of Celtic culture, customs and influence into modern times, and its revival once again today.