Man is social in his nature. He does not require to be caught and tamed in order to induce him to live with his fellows. The utter helplessness with which he enters the world, and the long period required for the maturity of his powers, necessitate the family relation; which, as we may observe, is wider, and in its extensions stronger, among the ruder than among the more cultivated peoples. The first societies are families, expanding into tribes, still holding a mutual blood relationship, and even when they have become great nations claiming a common descent. Given beings of this kind, placed on a globe of such diversified surface and climate as this, and it is evident that, even with equal capacity, and an equal start, social development must be very different. The first limit or resistance to association will come from the conditions of physical nature, and as these greatly vary with locality, corresponding differences in social progress must show themselves. The net rapidity of increase, and the closeness with which men, as they increase, can keep together, will, in the rude state of knowledge in which reliance for subsistence must be principally upon the spontaneous offerings of nature, very largely depend upon climate, soil, and physical conformation. Where much animal food and warm clothing are required; where the earth seems poor and niggard; where the exuberant life of tropical forests mocks barbarous man's puny efforts to control; where mountains, deserts, or arms of the sea separate and isolate men; association, and the power of improvement which it evolves, can at first go but a little way. But on the rich plains of warm climates, where human existence can be maintained with a smaller expenditure of force, and from a much smaller area, men can keep closer together, and the mental power which can at first be devoted to improvement is much greater. Hence civilization naturally first arises in the great valleys and table-lands where we find its earliest monuments.