Two needs have determined philosophical thinking about law. On the one hand, the paramount social interest in the general security, which as an interest in peace and order dictated the very beginnings of law, has led men to seek some fixed basis of a certain ordering of human action which should restrain magisterial as well as individual wilfulness and assure a firm and stable social order. On the other hand, the pressure of less immediate social interests, and the need of reconciling them with the exigencies of the general security, and of making continual new compromises because of continual changes in society, has called ever for readjustment at least of the details of the social order. It has called continually for overhauling of legal precepts and for refitting of them to unexpected situations. And this has led men to seek principles of legal development by which to escape from authoritative rules which they feared or did not know how to reject, but could no longer apply to advantage. These principles of change and growth, however, might easily prove inimical to the general security, and it was important to reconcile or unify them with the idea of a fixed basis of the legal order.