This is a practical manual for divination using the ancient Celtic characters of ogham writing. However, it is much more than that as well. It opens the doors to the authentic understanding of ancient Celtic cosmology and psychology in ways that have never been done before. This, as much as the divinatory material, opens the reader to vistas as yet uncharted in the fields of Celtic studies. The book contains a complete system of oghamic divination, the lore of each of the 20 ogham characters, a Celtic psychology and Celtic cosmology as well as a complete suggested curriculum for training in Celtic spirituality based on the ogham system. One of the most important new features of this edition is the information demonstrating the fact that the ogham system was not originally a "tree alphabet." This book is a thorough and substantial rewriting of a book by Edred Thorsson by the same name published more than a decade ago. This new edition takes into account important new findings in the realm of ogham studies and must be read and studied by all those who first read the older edition in order that a deeper and more authentic understanding can be reached.