The mind or soul of the older psychology was the cause not only of consciousness, but also of modifiability in thought and action. It was the substance or force in man whereby he was sensitive to certain events, was able to make certain movements, and not only had ideas but connected them one with another and with various impressions and acts. It was supposed to account for actual bodily action as well as for the action-consciousness. It explained the connections between ideas as well as their internal composition. If a modern psychologist defines mind as the sum total of consciousness, and lives up to that definition, he omits the larger portion of the task of his predecessors. To define our subject-matter as the nature and behavior of men, beginning where anatomy and physiology leave off, is, on the contrary, to deliberately assume responsibility for the entire heritage. Behavior includes consciousness _and_ action, states of mind _and_ their connections. Even students devoted to ‘consciousness as such’ must admit that the movements of an animal and their connections with other features of his life deserve study, by even their kind of psychologist. For the fundamental means of knowing that an animal has a certain conscious state are knowledge that it makes certain movements and knowledge of what conscious states are connected with those movements. Knowledge of the action-system of an animal and its connections is a prerequisite to knowledge of its stream of consciousness. There are better reasons for including the action-system of an animal in the psychologist’s subject-matter. An animal’s conscious stream is of no account to the rest of the world except in so far as it prophesies or modifies his action.[2] There can be no moral warrant for studying man’s nature unless the study will enable us to control his acts. If a psychologist is to study man’s consciousness without relation to movement, he might as well fabricate imaginary consciousnesses to describe and analyze. The lovers of consciousness for its own sake often do this unwittingly, but would scarcely take pride therein! The truth of the matter is, of course, that an animal’s mind is, by any definition, something intimately associated with his connection-system or means of binding various physical activities to various physical impressions. The whole series—external situations and motor responses as well as their bonds—must be studied to some extent in order to understand whatever we define as mind. The student of behavior, by frankly accepting the task of supplying any needed information not furnished by physiology, and of studying the animal in action as well as in thought, is surer of getting an adequate knowledge of whatever features of an animal’s life may be finally awarded the title of mind.