No understanding of the causes of stability and instability in human society is possible until the undiminished vigour of instinct in man is fully recognized. The significance of this rich instinctive endowment lies in the fact that mental health depends upon instinct finding a balanced but vigorous expression in functional activity. The response to instinct may be infinitely varied, and may even, under certain circumstances, be not more than symbolic without harm to the individual as a social unit, but there are limits beyond which the restriction of it to indirect and symbolic modes of expression cannot be carried without serious effects on personality. The individual in whom direct instinctive expression is unduly limited acquires a spiritual meagreness which makes him the worst possible social material. All recorded history shows that society developing under the conditions that have obtained up {245} to the present time—developing, that is to say, spontaneously under the random influences of an uncontrolled environment of the individual—does not permit to the average man that balanced instinctive expression which is indispensable for the formation of a rich, vigorous, and functionally active personality. It has been one of my chief efforts in this book to show that the social instinct, while in itself the very foundation of society, takes, when its action is undirected and uncontrolled, a principal part in restricting the completeness and efficacy of the social impulse. This instinct is doubly responsible for the defects which have always inhered in society through the personal impoverishment of its individual constituents. In the first place, it is the great agent by which the egoistic instincts are driven into dwarfed, distorted, and symbolic modes of expression without any regard for the objective social necessity of such oppressive regulation. In the second place, it is an instinct which, while it embodies one of the deepest and potentially most invigorating passions of the soul, tends automatically to fall out of vigorous and constant activity with the expansion of societies. It is the common character of large societies to suffer heavily from the restrictive effect on personality of the social instinct, and at the same time to suffer in the highest degree from the debilitation of the common social impulse. Only in the smallest groups, such as perhaps was early republican Rome, can the common impulse inform and invigorate the whole society. As the group expands and ceases to feel the constant pressure of an environment it no longer has to fear, the common impulse droops, and the society becomes segregated into classes, each of which a lesser herd within the main body and under the reciprocated pressure of its fellows, now yields to its members the social feeling which the main body {246} can no longer provide. The passage of the small, vigorous, homogeneous and fiercely patriotic group into the large, lax, segregated and