Nowhere more than in connection with our emotions are the close inter-relations of mind and body seen. All are familiar with the fact that the emotion of anger tends to find expression in the blow, love in the caress, fear in flight, and so on. But just how our organism acts in _producing_ an emotion is less generally understood. Professor James and Professor Lange have shown us that emotion not only tends to produce some characteristic form of response, but that _the emotion is itself caused by certain deep-seated physiological reactions_. Let us seek to understand this statement a little more fully. PHYSIOLOGICAL EXPLANATION OF EMOTION.--We must remember first of all that _all_ changes in mental states are accompanied by corresponding physiological changes. Hard, concentrated thinking quickens the heart beat; keen attention is accompanied by muscular tension; certain sights or sounds increase the rate of breathing; offensive odors produce nausea, and so on. So complete and perfect is the response of our physical organism to mental changes that one psychologist declares it possible, had we sufficiently delicate apparatus, to measure the reactions caused throughout the body of a sleeping child by the shadow from a passing cloud falling upon the closed eyelids. The order of the entire event resulting in an emotion is as follows: (1) Something is _known_; some object enters consciousness coming either from immediate perception or through memory or imagination. This fact, or thing known, must be of such nature that it will, (2) set up deep-seated and characteristic _organic response_; (3) the feeling _accompanying and caused by these physiological reactions constitutes the emotion_. For example, we may be passing along the street in a perfectly calm and equable state of mind, when we come upon a teamster who is brutally beating an exhausted horse because it is unable to draw an overloaded wagon up a slippery incline. The facts grasped as we take in the situation constitute the _first_ element in an emotional response developing in our consciousness. But instantly our muscles begin to grow tense, the heart beat and breath quicken, the face takes on a different expression, the hands clench--the entire organism is reacting to the disturbing situation; the _second_ factor in the rising emotion, the physiological response, thus appears. Along with our apprehension of the cruelty and the organic disturbances which result we feel waves of indignation and anger surging through us. This is the _third_ factor in the emotional event, or the emotion itself. In some such way as this are all of our emotions aroused. ORIGIN OF CHARACTERISTIC EMOTIONAL REACTIONS.--Why do certain facts or objects of consciousness always cause certain characteristic organic responses?