** This edition has a beautiful layout with a font size designed to make it easy to read *** "The object of this book is the study of the subconscious, normal or abnormal, individual or social, in its relation to suggestion and suggestibility; and let me hope that the thoughtful reader will find my work not only interesting, but stimulating to thought and useful in practical life" - Boris Sidis This work is divided into three parts: Suggestibility; The Self; Man as One of a Crowd. Under all these heads the author is original. He tries by ingenious experiments to show that the suggestibility of waking persons follows an opposite law to that of hypnotic subjects. Suggestions must be veiled, in the former case, to be effective; in the latter case, the more direct and open they are the better. By other ingenious experiments Dr. Sidis tries to show that the" subliminal" or "ultra-marginal" portions of the mind may in normal persons distinguish objects which the attentive senses find it impossible to name. These latter experiments are incomplete, but they open the way to a highly important psychological investigation. In Part II, on "The Self," a very full account is given of "double personality," subliminal consciousness, etc. In Part III the very important matter of "crowd psychology" is discussed, almost for the first time in English.