""Druidism"" by Alexander MacBain is a comprehensive study of the ancient Celtic religion of Druidism. The book delves into the history, mythology, and beliefs of the Druids, who were the spiritual leaders and intellectuals of the Celtic tribes in Europe. MacBain examines the role of the Druids in Celtic society, their practices and rituals, and their relationship with nature and the gods. He also explores the influence of Druidism on later religions,...