This is a definitive work on the subject. The author surpasses credible to the level of genuine expert. I feel safe in trusting his research and speculations. Being a scholarly work, the book isn't for the faint of heart (it can be thick reading at times), but if your into Celtic studies, the history of Ireland, the history of the Druids, then this book is a must and should be read and referred to again and again. The author uses a wonderful blend of archaeology, literature, and mythology not only of Ireland, but also from a vast range of sources. He ties in accounts of the Continental Celts, the Indo-Europeans, the Greek and Roman sources, and even accounts from India (Vedic, rig Veda, etc). The author gives us a complete picture that is supported by a myriad of sources and language associations. The only thing that I felt could have enhanced the book would be an index. Very great work, well worth the money.
O'Hogain has done it again, by providing another invaluable resource for those interested in learning more about Celtic and Irish pre-christian religion. Very well-researched and written, this book will take you on a journey back in time, which you'll never forget! Don't miss his other works either.