The Fairy Faith In Celtic Countries
But the purely social environment under which the Fairy-Faith of Wales survives is a potent force which promises to preserve underneath the surface of Welsh national life, where the commercialism of the age has compelled it to retire in a state of temporary latency, the ancestral idealism of the ancient Brythonic race. Read the book here
From the Wikipedia, Evans-Wentz :- "He was born as Walter Yeeling Wentz in Trenton, New Jersey in 1878. His father was a real estate businessman, of German descent, while his mother was Irish. He also had two brothers and two sisters. Though initially a Bapist, his father had turned to spiritualism and Theosophy. As a teenager he read Madame Blavatsky's Isis Unveiled and The Secret Doctrine at his father's library and became interested in the teachings of Theosophy and Occult. Subsequently, at the turn of century, he moved to San Diego in California, and joined his father's profession, but also because it was close to Lomaland, the American headquarters for the Theosophical Society, which he joined in 1901.
Evans-Wentz joined the Stanford University at the age of 24. Here he studied religion, philosophy and history and was deeply influenced by visitors William James and W. B. Yeats. He went on to receive B.A. and M.A degrees. He then studied Celtic mythology and folklore at Jesus College, Oxford (1907). He travelled across Wales, Scotland, Ireland, Cornwall, Brittany, and the Isle of Man collecting stories about pixies, fairies, and goblins, and published his thesis about Fairy Faith as a book, The Fairy-Faith in Celtic countries in 1911. At Oxford, he also added his mother's Welsh surname Evans to his name, being known henceforth as Evans-Wentz.