The chief object of this volume is to exhibit, in a manner acceptable to readers who are not specialists, the application of the principles and methods which guide investigations into popular traditions to a few of the most remarkable stories embodying the Fairy superstitions of the Celtic and Teutonic peoples. Some of the subjects discussed have already been dealt with by more competent inquirers. But even in these cases I have sometimes been able to supply additional illustrations of the conclusions previously arrived at, and occasionally, I hope, to carry the argument a step or two further than had been done before. I have thus tried to render the following pages not wholly valueless to students.