simply because we have by usage unwisely limited the meaning of the word _science_ to a knowledge of things material and visible, whereas it really means a knowing or a knowledge of everything which exists. We have tried to deal with the rare psychical experiences of Irish, Scotch, Manx, Welsh, or Breton seers, and psychics generally, in the clearest language possible; but if now and then we are charged with being mystical, this is our defence. III. THE METHOD OF STUDYING THE FAIRY-FAITH In this study, which is first of all a folk-lore study, we pursue principally an anthropo-psychological method of interpreting the Celtic belief in fairies, though we do not hesitate now and then to call in the aid of philology; and we make good use of the evidence offered by mythologies, religions, metaphysics, and physical sciences. Folk-lore, a century ago was considered beneath the serious consideration of scholars; but there has come about a complete reversal of scholarly opinion, for now it is seen that the beliefs of the people, their legends, and their songs are the source of nearly all literatures, and that their institutions and customs are the origin of those of modern times. And, to-day, to the new science of folk-lore,--which, as Mr. Andrew Lang says, must be taken to include psychical research or psychical sciences,--archaeology, anthropology, and comparative mythology and religion are indispensable. Thus folk-lore offers the scientific means of studying man in the sense meant by the poet who declared that the proper study of mankind is man. IV. DIVISIONS OF THE STUDY This study is divided into four sections or parts. The first one deals with the living Fairy-Faith among the Celts themselves; the second, with the recorded and ancient Fairy-Faith as we find it in Celtic literature and mythology; the third, with the Fairy-Faith in its religious aspects; and in the fourth section an attempt has been made to suggest how the theories of our newest science, psychical research, explain the belief in fairies. I have set forth in the first section in detail and as clearly as possible the testimony communicated to me by living Celts who either believe in fairies, or else say that they have seen fairies; and throughout other sections I have preferred to draw as much as possible of the material from men and women rather than from books. Books too often are written out of other books, and too seldom from the life of man; and in a scientific study of the Fairy-Faith, such as we have undertaken, the Celt himself is by far the best, in fact the only authority. For us it is much less important to know what scholars think of fairies than to know what the Celtic people think of fairies. This is especially true in considering the Fairy-Faith as it exists now. V. THE COLLECTING OF MATERIAL