The limits of civilization were primarily the mechanical limitations of man's ability to produce. So long as his only ways to drive machinery were by wind and water, the strength of domesticated animals, and his own brawn, it was almost impossible for him to accumulate sufficient reserves of food and clothing so that instead of thinking what he should eat and what he should put on, he could think a little of how to make life good. And whenever by some fortunate chance a group of men did get together a small hoard, parallel with the growth of each tiny surplus grew the hatred of the outside groups who wished to possess it, and the need to defend it by force. So that when here and there through the centuries pocketed civilizations did arise, they were civilizations perpetually armed for defence and with the sword in their hands. And though the spirit of man in such places as India and Egypt, in China, Persia, Palestine, Greece, Carthage, Rome, and the free Italian cities, as soon as the pressure was removed ever so little, did flower into religion and art and science, these favored oases were surrounded by crowding, hungry multitudes who pressed in and in till at last every one of these was overwhelmed. Before the coming of coal man had to satisfy his longing for peace and knowledge and companionship through his dreams. These have come down to us in the legends of India and Israel, China, Greece, and our own Nordic ancestors which perpetually play about the fabulous treasure--the Golden Fleece, the land of milk and honey, the Volsung's miraculous hoard--pathetic symbols of plenty, liberation, and the possibility of brotherhood. But until coal came there was no way to make these dreams come true. For survival was only to the strong, or to the cunning, or to those who were willing to grow fat on the leanness of others, and every respite from the basic business of keeping alive was extravagantly paid for either by oneself or another--before coal came. But with the coming of coal there rose the possibility of producing more than enough to keep everybody alive. A tireless bond servant had been given to the race whose power grew as it was called on, until now in the United States where coal is used most indefatigably, each family has the equivalent of thirty human servants, whose use does not need to involve the exploitation of man by man. For the first time there is the possibility of all having enough,--of a world surplus on which to base civilization.