As far as our sciences have been able to interpret, human experience and the phenomena of society, like the subhuman phenomena of nature, are transformations of physical energy. Life, whether in man, brute, or plant, is never a static thing: it is action. To the physiologist life consists ultimately in that ceaseless chemical change, metabolism, which goes on in the cells of the body in the two complementary forms, anabolism and katabolism. The form of life which the psychologist studies is the stream of consciousness which accompanies the katabolism in the cells of the brain. Katabolism, and consciousness along with it, sinks to low ebb when there is no stimulus from the environment; it rises to high activity when the environment gives keen stimulus. The form to activity which the sociologist studies is that which comes in response to stimulus from other persons. The entire theory of sociology may be, and to some extent must be, built up on this metabolic basis of stimulus and response.

Mention may be made here of habit, suggestibility, and imitation. Like mild but ever present stimuli they are important in society by determining action when there is no definite stimulus to the contrary. They cause the members of a society to think and act together without compulsion, thus laying the foundation for the principles of social organization, which are to be analyzed in Part II to follow.

But although action ordinarily awaits stimulus from the environment, it does not necessarily do so. There is such a thing as stimulus from within. This is best seen in the child. When the time comes for customary activity, say after a period of rest, if no stimulus comes from the environment, then restlessness sets in; the child goes out, as it were, to seek stimulus, and usually succeeds in finding it. The same principle holds with people of every age everywhere. There is always something to do. With the poor that something first of all is toil for subsistence. But the rich work just as hard, the difference being that they have more choice about what kind of work they will do. The rich man toils to win in the game of finance, not so much because he wants more money to spend, as because he has energy which he must expend. For the same reason the rich man's wife assumes a burden of dressing herself, and adorning her home, and entertaining, and calling, which is just as exhausting in its way as the toil of her sister in poverty. Persons of an aggressive disposition manage to get into some kind of conflict - a war, a political fight, industrial competition, social rivalry, or a neighborhood feud. One cause of the Crusades was the monotony of medieval village life which made the young men restless and ready for adventurous expeditions, while their neighbors who loved quiet had plenty of reason to encourage their going. When there are no real contests at hand, artificial ones come in the form of games and sports - tournament, football, or debating league. Mothers and teachers know well enough how all of this applies to children. Those who are preparing to be teachers need to have their attention called to it.

In a certain college the students had a great tendency to go out after the hour when they were expected to be in their rooms. With only their studies to enlist their interest inside, they very naturally found interesting things outside. Then the college officials thought best to organize clubs and societies which could be directed in part by members of the faculty. After that the mischief-making diminished.

This much, at least, has been learned, that desire is the all-pervading, world-animating principle, the universal nisus and pulse of nature, the mainspring of all action, and the life-power of the world. It is organic force. Its multiple forms, like the many forces of the physical world, are the varied expressions of one universal force. . . .

. . . Crime may be prevented by broadening the mind of the criminal with knowledge that he can never make any direct use of. . . . - L. F. Ward, Psychic Factors of Civilization, pp. 55, 203.

The aim should be to develop positive rather than negative morality, the presence of actual good works rather than the absence of wrongdoing. It is better for the school to teach a boy to earn money honestly than merely not to steal; better to teach him to plant a school garden and tend it than merely not to cut his initials in his desk; better to teach him to help younger children with their work and play than merely not to tease them. It is what the school gets boys and girls to do, not what it keeps them from doing, that counts most for morality. - Thorn-dike, Education, pp. 29, 30.

The simplest theory of play is the Schiller-Spencer surplus energy theory of play. According to this theory, animals play in order to get rid of the energy they have left over after they have completed the activities necessary for existence. . . .

If play is nothing more than the expenditure of surplus energy, it might be expected that it would be nothing more than formless activities. But as a matter of fact, playful activities take on very different forms, and these forms are suggestive of their nature and origin. The noticeable thing about them is that they resemble certain instinctive activities. Thus the plays of the boy seem to reveal the presence in him of the hunting and combative or pugnacious instincts, while the little girl playing with her dolls reveals . . . the maternal instinct. ... - Parmelee, Science of Human Behavior, pp. 248-250.

Interests are the stuff that men are made of. More accurately expressed, the last elements to which we can reduce the actions of human beings are the units which we may conveniently name "interests"...

. . . Human interests, then, are the ultimate terms of calculation in sociology. The whole life-process, so far as we know it, whether viewed in its individual or in its social phase, is at last the process of developing, adjusting, and satisfying interests. - Small, General Sociology, pp. 426, 433, 434.

That a maximal degree of efficiency in any line of work is inconsistent with gloom and depression is not only a common verdict of general experience, but a logical inference from scientific principles. It is a wellestablished law of psychology that a state of mind which is predominantly "pleasant" in its affective coloring is always accompanied by certain well-defined physiological phenomena: (1) an increase in the volume of the body, due to a distention of the capillaries running underneath the skin; (2) deeper breathing; (3) increased rate of pulse beat; and (4) increased muscular energy. A state of mind which is "unpleasantly" toned, on the other hand, is accompanied by bodily phenomena of the opposite character: decrease in bodily volume, lighter breathing, decreased rate of pulse beat, and decreased muscular energy.

The relation of these factors to efficiency is obvious. Hope and buoyancy simply mean, other things equal, a favorable condition for good work of any sort, while gloom and depression must, by the same token, form a heavy handicap in any line of endeavor. The old proverb, "Nothing succeeds like success," is thus seen to be, like so many other proverbs, a profound psychological law. The glow of satisfaction that comes from the consciousness of work well done sets free the energy that can be concentrated upon the new and more difficult task, thus multiplying the chances for a fresh triumph. And the sickening sense of failure will similarly choke up the channels of energy and multiply the chances for a second defeat. The man who, in the face of this handicap, can pluck success out of failure and victory out of defeat is the rarest of heroes.

It is needless to say that cheerfulness and encouragement should be the keynotes of instruction. ... - Bagley, The Educative Process, pp. 344, 345.