No successful attempt has heretofore been made to supply this want; nor has success been possible until within a very recent period, for the simple reason that previous to the discovery of certain facts in psychological science, the scientific world was without the necessary data from which a correct hypothesis could be formulated. The researches of Professor Liébault in the domain of hypnotism, seconded by those of his pupil, Professor Bernheim, have resulted in discoveries which throw a flood of light upon the whole field of psychological investigation. Their field of observation being confined to hypnotism, and chiefly to its employment as a therapeutic agent, it is not probable that either of those eminent scientists realized the transcendent importance of their principal discovery, or perceived that it is applicable to psychological phenomena outside the domain of their special studies. The discovery is this: _that hypnotic subjects are constantly amenable to the power of suggestion; that suggestion is the all-potent factor in the production of all hypnotic phenomena_. This proposition has been demonstrated to be true beyond the possibility of a reasonable doubt. In subsequent chapters of this book it will be shown that this fact supplies the missing link in the chain of propositions necessary for a complete working hypothesis for the subject under consideration. The general propositions applicable to all phases of psychological phenomena are here only briefly stated, leaving the minor, or subsidiary, propositions necessary for the elucidation of particular classes and sub-classes of phenomena to be stated under their appropriate heads. The first proposition relates to the dual character of man's mental organization. That is to say, man has, or appears to have, two minds, each endowed with separate and distinct attributes and powers; each capable, under certain conditions, of independent action. It should be clearly understood at the outset that for the purpose of arriving at a correct conclusion it is a matter of indifference whether we consider that man is endowed with two distinct minds, or that his one mind possesses certain attributes and powers under some conditions, and certain other attributes and powers under other conditions. It is sufficient to know that everything happens just as though he were endowed with a dual mental organization. Under the rules of correct reasoning, therefore, I have a right to assume that MAN HAS TWO MINDS; and the assumption is so stated, in its broadest terms, as the first proposition of my hypothesis. For convenience I shall designate the one as the _objective_ mind, and the other as the _subjective_ mind. These terms will be more fully explained at the proper time. The second proposition is, that THE SUBJECTIVE MIND IS CONSTANTLY AMENABLE TO CONTROL BY SUGGESTION. The third, or subsidiary, proposition is, that THE SUBJECTIVE MIND IS INCAPABLE OF INDUCTIVE REASONING. [Illustration]