Unity is the common desiderate of philosophic systems of all metaphysical types--neutral, materialistic, idealistic. But the dominant tradition has tended to think this unity in terms of _interest_, of _spirit_, of _mentality_. It has tended, in a word, to assimilate nature to human nature, to identify things with the _values_ of things, to envisage the world in the image of man. To it, the world is all spirit, ego, or idea; and if not such through and through, then entirely subservient, in its unhumanized parts, to the purposes and interests of ego, idea, or spirit. Why, is obvious. A world of which the One substance is such constitutes a totality of interest and purpose which faces no conflict and has no enemy. It is fulfilment even before it is need, and need, indeed, is only illusion. Even when its number is many, the world is a better world if the stuff of these many is the _same_ stuff as the spirit of man. For mind is more at home with mind than with things; the pathetic fallacy is the most inevitable and most general. Although the totality of spirit is conceived as good, that is, as actualizing all our desiderates and ideals, it would still be felt that, even if the totality were evil, and not God, but the Devil ruled the roost, the world so constituted must be better than one utterly non-spiritual. We can understand and be at home with malevolence: it offers at least the benefits of similarity, of companionship, of intimateness, of consubstantiality with _will_; its behavior may be foreseen and its intentions influenced; but no horror can be greater than that of utter aliency. How much of religion turns with a persistent tropism to the consideration of the devil and his works, and how much it has fought his elimination from the cosmic scheme! Yet never because it loved the devil. The deep-lying reason is the fact that the humanization of Evil into Devil mitigates Evil and improves the world. Philosophy has been least free from this corrective and spiritizing bias. Though it has cared less for the devil, it has predominantly repudiated aliency, has sought to prove spirit the cause and substance of the world, and in that degree, to transmute the aliency of nature into sameness with human nature.