The first six chapters of the present volume are composed from six articles prepared for the Atlantic Monthly, and published in that magazine in 1868. They attracted quite as much attention as the writer anticipated, and this has induced him to enlarge them, and add other chapters. His aim is to enable the reader to become acquainted with the doctrines and customs of the principal religions of the world, without having to consult numerous volumes. He has not come to the task without some preparation, for it is more than twenty-five years since he first made of this study a speciality. In this volume it is attempted to give the latest results of modern investigations, so far as any definite and trustworthy facts have been attained. But the writer is well aware of the difficulty of being always accurate in a task which involves such interminable study and such an amount of details. He can only say, in the words of a Hebrew writer: "If I have done well, and as is fitting the story, it is that which I desired; but if slenderly and meanly, it is that which I could attain unto."