Reason’s function in defining the ideal is in principle extremely simple, although all time and all existence would have to be gathered in before the applications of that principle could be exhausted. A better example of its essential working could hardly be found than one which Darwin gives to illustrate the natural origin of moral sense. A swallow, impelled by migratory instincts to leave a nest full of unfledged young, would endure a moral conflict. The more lasting impulse, memory being assumed, would prompt a moral judgment when it emerged again after being momentarily obscured by an intermittent passion. “While the mother bird is feeding or brooding over her nestlings, the maternal instinct is probably stronger than the migratory; but the instinct which is more persistent gains the victory, and at last, at a moment when her young ones are not in sight, she takes flight and deserts them. When arrived at the end of her long journey, and the migratory instinct ceases to act, what an agony of remorse each bird would feel if, from being endowed with great mental activity, she could not prevent the image continually passing before her mind of her young ones perishing in the bleak north from cold and hunger.”[E] She would doubtless upbraid herself, like any sinner, for a senseless perfidy to her own dearest good. The perfidy, however, was not wholly senseless, because the forgotten instinct was not less natural and necessary than the remembered one, and its satisfaction no less true. Temptation has the same basis as duty. The difference is one of volume and permanence in the rival satisfactions, and the attitude conscience will assume toward these depends more on the representability of the demands compared than on their original vehemence or ultimate results. [Sidenote: Conscience and reason compared.] A passionate conscience may thus arise in the play of impulses differing in permanence, without involving a judicial exercise of reason. Nor does such a conscience involve a synthetic ideal, but only the ideal presence of particular demands. Conflicts in the conscience are thus quite natural and would continually occur but for the narrowness that commonly characterises a mind inspired by passion. A life of sin and repentance is as remote as possible from a Life of Reason. Yet the same situation which produces conscience and the sense of duty is an occasion for applying reason to action and for forming an ideal, so soon as the demands and satisfactions concerned are synthesised and balanced imaginatively. The stork might do more than feel the conflict of his two impulses, he might do more than embody in alternation the eloquence of two hostile thoughts. He might pass judgment upon them impartially and, in the felt presence of both, conceive what might be a union or compromise between them.