Lawyers begin to generalize and to frame conscious theories in the later part of the stage of the strict law. At first these theories are analytical rather than philosophical. The attempt is to frame general formulas by which the rigid rules of the strict law may be reconciled where they overlap or conflict or may be distinguished in their application where such overlapping or conflict threatens. By this time, the crude beginnings of liability in a duty to compound for insult or affront to man or gods or people, lest they be moved to vengeance, has developed into liability to answer for injuries caused by oneself or done by those persons or those things in one's power, and liability for certain promises made in solemn form. Thus the basis of liability has become twofold. It rests on the one hand upon duty to repair injury. It rests on the other hand upon duty to carry out formal undertakings. It is enough for this stage of legal development that all cases of liability may be referred to these two types and that useful distinctions may be reached therefrom. Consideration of why one should be held to repair injury, and why he should be held to formal undertakings, belongs to a later stage. Juristic theory, beginning in the transition from the strict law to the stage of equity or natural law, becomes a force in the latter stage. As the relations with which the law must deal become more numerous and the situations calling for legal treatment become more complicated, it is no longer possible to have a simple, definite, detailed rule for every sort of case that can come before a tribunal, nor a fixed, absolute form for every legal transaction. Hence, under the leadership of philosophical jurists, men turn to logical development of the "nature" or ideal form of situations and to ethical ideas of what "good faith" or "good conscience" demands in particular relations or transactions. The strict law, relying on rule and form, took no account of intention as such. The words took effect quite independently of the thought behind them. But as lawyers began to reflect and to teach something more than a class or professional tradition, as they began to be influenced by philosophy to give over purely mechanical methods and to measure things by reason rather than by arbitrary will, emphasis shifted from form to substance; from the letter to the spirit and intent. The statute was thought of as but the lawmaker's formulation of a principle of natural law. It was not the _uerba_ that were efficacious, as in the strict law, which had inherited the primitive faith in the power of words and thought of the legal formula as if it were a formula of incantation possessing inherent magical force. It was the _ratio iuris_, which transcended words and formulas. So also the traditional rule was not a magic formula discovered by our fathers. It was a customary expression of a principle of natural law. Likewise the formal transaction was not a