years. And high judicial authority lately expressed the opinion, a propos of a change in standard time, that usage may alter itself in a day as well as in a century, and be as authoritative in one case as in the other. Nothing feels older than a well-established custom, however recent it may be.
Conscience then cannot be recognized as infallible merely through the test of antiquity as judged by our feeling. Conscience furthermore, or emotions that pretend to the authority of conscience, may be found counseling or approving contradictory ways of action. Therefore conscience is no sufficient moral guide.
But even if all this were waived, if conscience were in actual agreement among all men, and if there were no difficulty in distinguishing the voice of conscience from the voice of passion, or from other prejudices or sentiments, it would remain true that no ultimate theory of the difference between right and wrong could be founded on the assertions of any instinct. Why an individual should obey his conscience unless he wishes to do so, cannot be made clear by conscience itself alone. Nor can the necessity and real truth of a distinction be made clear by the assertions of a faculty that, however dignified it may be, appears in the individual as a personal emotion, a prejudice or choice, determined by an impulse in him. Even if other people actually have this same impulse, that does not make their common prejudice necessary or rational. Conscience, if universal, would still be only a physical fact. If there are actually no differences among various consciences,
