This book depends chiefly upon the oral and written testimony so freely contributed by its many Celtic authors, The Peasant and the Scholar, the Priest and the Scientist, The Poet and the Business Man, the Seer and the Non Seer, and in honour of them I dedicate it to two of the Brethren in Ireland A.E. whose unwavering loyalty to the Fairy-Faith has inspired much that I have herein written, whose friendly guidance in my study of Irish mysticism I most gratefully acknowledge; and William Butler Yeats, who brought me at my own Alma Mater in California the first message from Fairyland, and who afterwards in his own country led me through the haunts of Fairy Kings and Queens.