This is the tendency of animals of a given species to keep together, as in herds of cattle, flocks of birds, schools of fishes, swarms of insects. These, however, are only the extreme forms of it; it runs in some degree through all grades of animal and vegetable life. It is in fact necessary to life of any kind as we know it. Life exists only in individuals, and each of these exists for only a limited period; each individual is born, lives his period, and dies.

By turns we catch the vital breath, and die. - Pope, Essay on Man, Epistle III.

But life comes only from life; omne vivutm e vivo, is the old phrase of the biologists. Every individual has parents, and in the ordinary course of things will have offspring. The result is that if a given species is found in a given locality at all, it is usually found in as large numbers as the locality can support. Accordingly, the individuals must be able to get along with their kind as well as with their natural environment, and they just as much become adapted to depending on their kind. Many species depend on group activity to get their food, rear their young, and protect themselves. Each animal is guided by instinct to those forms of associating with its kind which are necessary for its habitat. It may have no foresight in the matter; it merely feels uneasy when alone all the time, and is content when in company. The lion, for example, hunts alone, but rests in his den with mate and young. The wolf, on the other hand, hunts with the pack. The proposition, therefore, holds that life is fundamentally social, though in varying degrees and with partial exceptions. When Aristotle wrote that "man is a social animal," he was stating a principle of broader scope than he probably thought.

One summer a single sprout of corn came up in my garden. It grew into a fine stalk with two large ears, but produced only a few kernels. I have also found that a single row of corn does not produce well. Corn must be massed in a field to be at its best.

So of human beings. The German proverb, Ein Mensch ist kein Mensch, "One man is no man," is literally true as far as mental development is concerned. Man becomes properly man only in connection with his fellows. Teachers and parents sometimes get out of patience with the propensity of children to watch one another, study together, follow a crowd, or go off in troops to play; also with their reluctance to stay alone or work independently. But such impatience should be held in restraint with the thought that this social propensity has been bred into children from the foundation of the world, and can be overcome, where necessary, only by much discipline. In this matter as in many others, the conditions of modern life make requirements that are contrary to man's original nature.

No creature is so gregarious as man, and we can hardly conceive him except as a member of the family and emerging, as the boy and girl now do, to become a socius in tribe, society, or political and industrial communities. - Hall, Adolescence, Vol. II, p. 363.

. . . Assertion of personality in distinction from other personality and exchange of recognitions of personal valuation, are as proper incidents of human satisfaction as supply of the bodily demand for food and air. - Small, General Sociology, p. 461.