May those who find in it their most cherished beliefs questioned or contemned, their surest consolations set at naught, remember that he had not shrunk from pain and anguish to himself, as one by one he parted with portions of that faith which in boyhood and early youth had been the mainspring of his life. Let them remember that, however many the years granted to him on earth might have been, his search after truth would have ended only with his existence; that he would have been the first to call for unsparing examination of his own opinions, arguments, and conclusions; the first to welcome any new lights thrown by other workers in the same field on the mysteries of our being and of the universe. Let them remember that while he assails much which they reckon unassailable, he does so in what to him is the cause of goodness, nobleness, love, truth, and of the mental progress of mankind. Let them remember that the utterance of that which, after earnest and laborious thought he deemed to be the truth, was to him a sacred duty; and may they feel, as he would have felt, the justness of these words of a good man and unswerving Christian lately passed away: "A man's charity to those who differ from him upon great and difficult questions will be in the ratio of his own knowledge of them: the more knowledge, the more charity." F. R. _INSCRIBED,_ _With all reverence and all affection, to the memory of the ever-lamented wife whose hearty interest in this book was, during many years of preparatory toil, my best support; whose judgment as to its merits or its faults would have been my most trusted guide; whose sympathy my truest encouragement; whose joyous welcome of the completed work I had long looked forward to as my one great reward: whose nature, combining in rare union scientific dearness with spiritual depth, may in some slight degree have left its impress on the page, though far too faintly to convey an adequate conception of one whose religious zeal in the cause of truth was rivaled only by the ardor of her humanity and the abundance of her love._ RAVENSCROFT, _November 1875_. TABLE OF CONTENTS. PAGE. GENERAL INTRODUCTION 19 _BOOK I._ EXTERNAL MANIFESTATIONS OF RELIGIOUS SENTIMENT. INTRODUCTION TO BOOK I. 27 FIRST PART. MEANS OF COMMUNICATION UPWARDS.