The attempt to exhibit the history of a certain phase of religious life through the irregular medium of fiction, dialogue, and essay, may appear to some a plan too fanciful for so grave a theme. But it must be remembered, that any treatment of such a subject which precluded a genial exercise of the imagination would be necessarily inadequate, and probably unjust. The method adopted appeared also best calculated to afford variety and relief to topics unlikely in themselves to attract general interest. The notes which are appended have been made more copious than was at first designed, in order that no confusion may be possible between fact and fiction, and that every statement of importance might be sustained by its due authority. It is hoped that, in this way, the work may render its service, not only to those who deem secondary information quite sufficient on such subjects, but also to the scholar, who will thus be readily enabled to test for himself my conclusions, and who will possess, in the extracts given, a kind of anthology from the writings of the leading Mystics. To those familiar with such inquiries it may perhaps be scarcely necessary to state that I have in no instance allowed myself to cite as an authority any passage which I have not myself examined, with its context, in the place to which I refer. In the _Chronicle of Adolf Arnstein_ the minimum of invention has been employed, and no historical personage there introduced utters any remark bearing upon Mysticism for which ample warrant cannot be brought forward. Wherever, in the conversations at Ashfield, any material difference of opinion is expressed by the speakers, Atherton may be understood as setting forth what we ourselves deem the truth of the matter. Some passages in these volumes, and the substance of the chapters on Quietism, have made their appearance previously in the pages of one of our quarterly periodicals. It should be borne in mind that my design does not require of me that I should give an account of all who are anywhere known to have entertained mystical speculation, or given themselves to mystical practice. I have endeavoured to portray and estimate those who have made epochs in the history of Mysticism, those who are fair representatives of its stages or transitions, those whose enthusiasm has been signally benign or notoriously baneful. I have either mentioned by name only, or passed by in silence, the followers or mere imitators of such men, and those Mystics also whose obscure vagaries neither produced any important result nor present any remarkable phænomena. Only by resolute omission on this principle has it been possible to preserve in any measure that historical perspective so essential to the truth of such delineations.