Book excerpt: Scant records remain of the ancient Celtic religion beyond some eleventh- and twelfth-century written material from the Irish Celts and the great Welsh document Mabinogion. This classic study by a distinguished scholar, builds not only upon the surviving texts but also upon folk customs derived from the rituals of the old cults. A masterly and extremely readable survey, it offers a reconstruction of the essentials of Celtic paganism: fascinating glimpses into primitive forms of worship involving rites centered on rivers and wells, trees and plants, and animals; and examinations of evidence from Celtic burial mounds to explore beliefs and customs related to the culture of the dead, including rites of rebirth and transmigration.