The Druids have been known and discussed for at least 2400 years, first by Greek writers and later by the Romans, who came in contact with them in Gaul and Britain. According to these sources, they were a learned caste who officiated in religious ceremonies, taught the ancient wisdoms, and were revered as philosophers. But few figures flit so elusively through history, and the Druids remain enigmatic and puzzling to this day. In this Very Short Introduction,...