Now there is a sense in which human nature is the same, generation after generation. But there is another sense in which human nature is undergoing constant alteration, and, indeed, it is one of the outstanding features of social life that it should be so. So far as can be seen there exists no difference between the fundamental capacities possessed by man during at least the historic period. There are differences in people between the relative strengths of the various capacities, but that is all. An ancient Assyrian possessed all the capacities of a modern Englishman, and in the main one would feel inclined to say the same of them in their quantitative aspect as well as in their qualitative one. For when one looks at the matter closely it is seen that the main difference between the ancient and the modern man is in expression. Civilization does not so much change the man so much as it gives a new direction to the existing qualities. Whether particular qualities are expressed in an ideally good direction or the reverse depends upon the environment to which they react. To take an example. The fundamental evil of war in a modern state is that it expends energy in a harmful direction. But war itself, the expression of the war-like character, is the outcome of pugnacity and the love of adventure without which human nature would be decidedly the poorer, and would be comparatively ineffective. It is fundamentally an expression of these qualities that lead to the quite healthy taste for exploration, discovery, and in intellectual pursuits to that contest of ideas which lies at the root of most of our progress. And what war means in the modern State is that the love of competition and adventure, the pugnacity which leads a man to fight in defence of a right or to redress a wrong, and without which human nature would be a poor thing, are expended in the way of sheer destruction instead of through channels of adventure and healthy intellectual contest. Sympathies are narrowed instead of widened, and hatred of the stranger and the outsider, of which a growing number of people in a civilized country are becoming ashamed, assumes the rank of a virtue. In other words, a state of war creates an environment--fortunately for only a brief period--which gives a survival value to such expressions of human capacity as indicate a reversion to a lower state of culture. We may put the matter thus. While conduct is a function of the organism, and while the _kind_ of reaction is determined by structure, the _form_ taken by the reaction is a matter of response to environmental influences. It is this fact which explains why the capacities of man remain fairly constant, while there is a continuous redirecting of these capacities into new channels suitable to a developing social life.