For the hope of an ultimate happy state on this planet to be enjoyed by future generations--or of some state, at least, that may relatively be considered happy--has replaced, as a social power, the hope of felicity in another world. Belief in personal immortality is still very widely entertained, but may we not fairly say that it has ceased to be a central and guiding idea of collective life, a criterion by which social values are measured? Many people do not believe in it; many more regard it as so uncertain that they could not reasonably permit it to affect their lives or opinions. Those who believe in it are doubtless the majority, but belief has many degrees; and one can hardly be wrong in saying that, as a general rule, this belief does not possess the imaginations of those who hold it, that their emotions react to it feebly, that it is felt to be remote and unreal, and has comparatively seldom a more direct influence on conduct than the abstract arguments to be found in treatises on morals. Under the control of the idea of Progress the ethical code recognised in the Western world has been reformed in modern times by a new principle of far-reaching importance which has emanated from that idea. When Isocrates formulated the rule of life, "Do unto others," he probably did not mean to include among "others" slaves or savages. The Stoics and the Christians extended its application to the whole of living humanity. But in late years the rule has received a vastly greater extension by the inclusion of the unborn generations of the future. This principle of duty to posterity is a direct corollary of the idea of Progress. In the recent war that idea, involving the moral obligation of making sacrifices for the sake of future ages, was constantly appealed to; just as in the Crusades, the most characteristic wars of our medieval ancestors, the idea of human destinies then in the ascendant lured thousands to hardship and death.