command a somewhat general interest. The prominence of the discussion of unfortunate and misleading tendencies in psychological opinion should not be allowed to obscure the more intrinsically important problems which in the main are of a different, though possibly not of an unrelated character. I should be defeating one of the purposes of these essays if, by the discussion of mooted positions, I conveyed the notion that the problems thus presented were naturally the fundamental ones about which advance in psychology may be most promisingly centred. I deeply regret that the dispossession of fable requires more resolute and more elaborate exposition than the unfoldment of fact; but such is part of the condition confronting the critical student of psychological opinion. I must depend upon the reader to make due allowances for this foreshortening of a portion of the composition, and so to bring away a truer impression of the whole than the apparent perspective suggests.

It would not be proper to claim for this budget of psychological studies a pre-arranged unity of design or a serial unfoldment of argument. They represent the unity of interest of a worker in a special field, who has his favorite excursions and vistas, who at times ventures away from the beaten paths and as frequently returns along those already traversed, but with varying purposes, and reaches the outlook from a different approach. There seems enough of singleness of purpose in the several presentations to warrant their inclusion in a single volume with a common name. There is enough also to make it pertinent to explain that the occasional repetitions of the same line of thought seemed less objectionable than frequent reference from one essay to another.

All of the essays have been previously printed in the pages of various scientific and popular magazines; and I have accordingly to acknowledge the courtesy of the several publishers, which makes possible their appearance in their present form. The essays have, however, been subjected to a critical revision, in the hope of increasing their acceptability in regard to form and material, and of giving them a setting appropriate to the interests of the present-day readers of psychological literature. Both in the selection of the essays from a larger group of published studies, and in their arrangement and elaboration, I have attempted to bear in mind the several current interests in questions of this type, and to direct these interests formatively along lines which seem to me fertile in promise and sterling in value. In the recasting thus made necessary it has come about (markedly in two cases, The Problems of Psychical Research and The Logic of Mental Telegraphy) that some of the essays have been entirely rewritten and bear only a generic resemblance to their former appearance.

The several acknowledgments to be recorded are as follows: To the "Popular Science Monthly," for permission to reprint The Psychology of Deception (December, 1888), The Psychology of Spiritualism (April, 1889), A Study of Involuntary Movements (April and September, 1892), The Mind's Eye (January, 1899), The Modern Occult (September, 1900); to the "New Princeton Review," for The Dreams of the Blind (January, 1888); to "Harper's Monthly Magazine," for The Problems of Psychical Research (June, 1889); to "Scribner's Magazine," for The Logic of Mental Telegraphy (October, 1895); to the "Cosmopolitan," for Hypnotism and its Antecedents (February, 1896). The Natural History of Analogy was delivered as a vice-presidential address before the Section of Anthropology of the American Association for the Advancement of Science, and was printed in its Proceedings, vol. xl., 1891. The article, Mental Prepossession and Inertia, appeared in a college publication of the University of Wisconsin, the "Aegis" (April, 1897). I have also to acknowledge my indebtedness to Miss Helen Keller for her very interesting contribution to my presentation of the dreams of the blind. My most comprehensive obligation in the preparation of the volume I have acknowledged upon the dedicatory page.

JOSEPH JASTROW.

Madison, Wisconsin, November, 1900.

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