But at a later date customs grew corrupt, and no longer sufficed to protect public good faith and morality, which were driven to seek asylum and sanction in the law, and so began gradually to modify its primitive character. Substance now prevailed over form, equity over the ancient text of the law, the intention of the contracting parties over words uttered by mistake; the law became more moral as customs grew more degraded. This transformation, though very gradual at the beginning, was afterward, accelerated by the new conditions of the Republics in which a change took place not unlike that occurring in the history of jurisprudence, towards the beginning of the seventeenth century. At that time the various European States, with their various systems of law, having contracted new relations with one another, came to recognise the necessity of establishing some fixed rules by which all should be bound, and thus, under the auspices of Hugh Grotius, the so-called School of Natural Law was built up. The same occurred in Rome, if not in the science, at any rate in the practice of law. As the dominion of the Republic became extended in Italy, its relations increased with neighbouring nations, among whom the more philosophical and less severe laws and principles of the Greek jurisprudence prevailed. It was impossible to impose upon all these nations, without modification, the rigid law of the Roman patriciate. Accordingly a new system of law, of a simpler character and wider reach, took shape and rapidly grew. This was named the _jus gentium_, to distinguish it from the other, the _jus civile_. "Jus gentium est quod naturalis ratio inter omnes homines constituit." This system, however, was not deduced from philosophic theories concerning human nature, as was the, appropriately styled, natural law of the eighteenth century; it originated in the practical needs of the Romans and their new relations with other Italian peoples: it was fostered by the principles of Greek jurisprudence that had been transplanted into Southern Italy; it met the new requirements of the Romans themselves; and taking the place that custom had previously filled in the Roman courts, grew side by side with the law of the Patricians with which it long maintained its union.