The subconscious now belongs to popular speech and it is the fashion of the day to speak of it glibly enough, but I fear it means very little to the average person. It is involved in vagueness if not mystery. Yet as a necessary induction from observed facts it has a very precise and concrete meaning devoid of abstruseness, just as the other has a precise and concrete meaning. Although subconscious processes were originally postulated on theoretical grounds, the theory is fortunately open to experimental tests so that it is capable of being placed on an experimental basis like other concepts of science. It is possible to artificially create such processes and study their phenomena; that is to say, the modes in which they manifest their activities, their influence upon conscious and bodily processes. We can study their effect in inhibiting and distorting thought, in determining it in this or that direction, in creating hallucinatory, emotional, amnesic, and other mental phenomena, in inducing physiological disturbances of motion, sensation, of the viscera, etc. We can also study the capabilities and limitations of the subconscious in carrying on intelligent operations below the threshold of consciousness. Again, we can investigate the phenomena of this kind as met with in the course of clinical observations, and by technical methods of research explore the subconscious and thus explicitly reveal the process underlying and inducing the phenomena. By such methods of investigation the subconscious has been removed from the field of speculative psychology, and placed in the field of experimental research. We have thus been enabled to postulate a subconscious process as a _definite concrete process producing very definite phenomena_. These processes and their phenomena have become a field of study in themselves and, from my point of view, the determination of the laws of the subconscious should be approached by such experimental and technical methods of research. After its various modes of activity, its capabilities and limitations have been in this way established, its laws can then be applied to the solution of conditions surrounding particular problems. Though we can determine the actuality of a particular subconscious process this does not mean that we can determine all the components of that process; we may be able to determine many or perhaps none of these: just as among the constituents of a crowd we may discern an active, turbulent group creating a disturbance, though we may not be able to recognize all the components of the group or the scattered individuals acting in conjunction with it. Nor may we be able to determine the intrinsic nature of a subconscious process—whether it is a conscious or unconscious one, but only the actuality of the process, the conditions of its activity, and the phenomena which it induces.