To turn back now to philosophy. An ultimate datum, even though it be logically unrationalized, will, if its quality is such as to define expectancy, be peacefully accepted by the mind; while if it leave the least opportunity for ambiguity in the future, it will to that extent cause mental uneasiness if not distress. Now, in the ultimate explanations of the universe which the craving for rationality has elicited from the human mind, the demands of expectancy to be satisfied have always played a fundamental part. {80} The term set up by philosophers as primordial has been one which banishes the incalculable. 'Substance,' for example, means, as Kant says, _das Beharrliche_, which will be as it has been, because its being is essential and eternal. And although we may not be able to prophesy in detail the future phenomena to which the substance shall give rise, we may set our minds at rest in a general way, when we have called the substance God, Perfection, Love, or Reason, by the reflection that whatever is in store for us can never at bottom be inconsistent with the character of this term; so that our attitude even toward the unexpected is in a general sense defined. Take again the notion of immortality, which for common people seems to be the touchstone of every philosophic or religious creed: what is this but a way of saying that the determination of expectancy is the essential factor of rationality? The wrath of science against miracles, of certain philosophers against the doctrine of free-will, has precisely the same root,--dislike to admit any ultimate factor in things which may rout our prevision or upset the stability of our outlook.