Those feelings which are based on associated ideas, and which rise at once to great intensity, are called emotions. This definition is somewhat deficient in so far as it is difficult to draw the line which exactly separates great from small intensity and a quick from a slow rise of intensity. Nevertheless, the stormy character of certain feelings not directly attached to sensory stimulation is so conspicuous that a special name is desirable. Anger, fright, distress, and hilarity are such feelings: hilarity distinctly pleasant, fright and distress equally unpleasant; anger also unpleasant, yet mixed sometimes with a certain amount of pleasure. The feeling and the consciousness of its cause are usually so intense in an emotion that there is little room for coherent thought. The judgment of a person in a state of emotion is narrow; his actions may be called shortsighted. Those feelings which become separated from their original perceptual or ideational substratum and attach themselves to any other kind of perception or ideation--no matter what feelings properly belong to these--are called moods. They are usually, probably because of the separation mentioned, of small intensity. But their duration is often very extended. As typical examples may be mentioned grudge, worry, dejection, and cheerfulness. Like all feelings, emotions and moods are in some way related to motor activity. Of particular interest here are not the purposive movements, which are by no means absent, but a large number of muscular activities seemingly of little or no usefulness, resulting from inherited nervous connections. In so far as these muscular activities become outwardly noticeable they are called the expressions of the emotions or moods. The angry man instinctively clinches his fist, the hilarious fellow dances about. Laughing, weeping, wrinkling of the forehead, and blushing are further expressions of this class. Contraction of the muscle fibers in the skin causes goose flesh, or the hair to stand on end. Breathing undergoes changes, becoming quicker or slower than normal. The blood vessels expand or diminish in size through the activity of the muscle fibers in their walls, causing the subject to look red or pale, to feel warm or cold, and in the latter case to shiver. Secretion of saliva, perspiration, and secretion of the lachrymal glands may result from the changes in the circulation of the blood. Fatigue, nausea, lack of appetite, and other symptoms of internal processes may occur.