The intention of this book is to lay stress on ideas and tendencies that have to be understood and appreciated, rather than on facts that have to be learned by heart. Many authors are not mentioned and others receive scanty treatment, because of the necessities of this method of approach. The book aims at dealing with the matter of authors more than with their lives; consequently it contains few dates. All that the reader need require to help him have been included in a short chronological table at the end. To have attempted a severely ordered and analytic treatment of the subject would have been, for the author at least, impossible within the limits imposed, and, in any case, would have been foreign to the purpose indicated by the editors of the Home University Library. The book pretends no more than to be a general introduction to a very great subject, and it will have fulfilled all that is intended for it if it stimulates those who read it to set about reading for themselves the books of which it treats.