There were thus two systems of law in force in Rome; and we accordingly find on the one hand judges and courts faithful to the ancient formalism, on the other, judges and courts taking cognizance of equity and good faith, and almost discharging the duties of the Censor. The continuous onward progress of the _jus gentium_, the reciprocal action of the two legal systems ultimately fusing them into one, wherein the old Roman formation gradually lost its rigidity, and equity, becoming incorporated with the civil law, began to assume a more definite and regular form, were all consequences of the principle which dominates the life and history of the Roman law, and may even be said to constitute it. For it has been moulded and diffused through the world, inheriting from the old Quirites its frame of iron; from contact with other races and from such germs as it could assimilate of Greek civilisation, its more comprehensive and human spirit. Assuming thus a character at once exact and philosophical, it seemed as though destined to become, from its superiority, the universal jurisprudence, the indispensable foundation, as it were, of all future legislation. This union of legal systems was effected by the Prætor. He it was who represented both the modern spirit and the ancient, enlarging the old law with the defences of equity which he strengthened by submitting it to the trammels of a formal procedure. This in substance was what took place with regard to customs, letters, and everything else. The fusion of Greek civilisation with the Roman constitutes the history of the ancient world. III.