This comprehensive study of the Druids offers a fresh look at the enigmatic and often controversial question of the role of these priests in Celtic society. The religion of Druidism is examined as an inheritance of Indo-European tradition, with intriguing analogies made between Irish and Roman cultic practices. The author identifies the functions of the ancient priests, providing an inventory of their duties and services. Druids are also defined in terms of their connections with other branches of Eurasian mysticism. This study will be of particular interest to scholars of Irish culture, Celtic culture, and comparative religion.