OF the eleven essays here reprinted the first seven are devoted to a common subject, viz. the so-called “occult” side of mental life and its significance for psychology. Prof. Jastrow's attitude towards the whole problem is marked by a luminous common sense which is, unfortunately, rarer even among serious psychologists than it should be. For scientific psychology the real question, as he never tires of pointing out, is not how to explain the marvels of spiritualism and allied arts, but how to account for the existence and wide diffusion of the state of mind which can believe in them. It is for the expert in conjuring tricks to show how the feats of the medium and the miracle-worker are done; the task of the psychologist is to investigate the “Psychology of Deception.” Incidentally, however, such papers as Prof. Jastrow's essays on “The Psychology of Spiritualism” and ”Hypnotism and its Antecedents,” besides throwing light on the mental condition of the deceived, are interesting as showing how more than one famous occultist has executed his deceptions. The latter of the two papers just named brings out clearly and well the enormous difference between the spirit and methods of science and of superstition in dealing with one and the same set of facts. In the essay on “The Problems of Psychical Research” Prof. Jastrow is perhaps on more debatable ground, though his attitude seems to the present reviewer at least the only scientific one. Briefly his position may be summed up thus: the psychologist, as such, has no in terest in the facts of “telepathy” except in so far as they throw light, as any facts about abnormal mental states may, on the known laws of normal mental processes. The “psychical researcher,” on the other hand, thinks his facts sufficient warrant for postulating types of mental process of which normal life reveals nothing. Hence, unlike the psychologist, he approaches the facts in a non-scientific spirit. In a subsequent “Study of Involuntary Movements,” conclusive experimental proof is given of the dependence of “thought-reading” performances upon unconscious movements of the muscles of the “subject” towards the object on which attention is directed. Of the remaining papers the most suggestive is perhaps that on “The Dreams of the Blind.”Fact and Fable in Psychology.By Joseph Jastrow. Pp. xi + 375. (Boston and New York: Houghton, Mifflin and Co., 1900.)