million years. Human skeletons have been found among the strata of former geological ages and associated with the bones of such prehistoric animals as mammoths and cave-bears. They were tree-climbers and tree-food eaters, at first, those semi-human progenitors of ours, and in their encounters with the giant-cats of the tropics developed that dread of darkness and night-hags still haunting our mental condition, with all its instinctive love of forest-life. Venturing further and further from their equatorial birthlands, our primitive ancestors became hunters; then nomadic herders, and finally stock-farmers, trying their luck with various methods of agriculture.
During that infinite series of generations the beings that evolved our organism may have strayed into strange forms of idolatry and refuted the belief in the universality of moral institutions; but they certainly did not fail to worship the goddess of health in her own temples. They were runners, swimmers, leapers, hill-climbers, wrestlers, boxers, and spearmen; outdoor exercise yielded them both the means of life and the opportunities for recreation. And it would be a mistake to suppose that the brief era of indoor life had modified our physical con-
