The conspirators had failed, and foreign enemies had failed, to overthrow the Medici, and their failure necessarily strengthened the dynasty against which these strenuous [Sidenote: Constitutional changes in 1480.] attacks had been directed. In 1480 Lorenzo was able to carry through vital changes in the constitution which for the rest of his life secured his authority against serious attack. It is noteworthy that no use was made of the parliament, as on previous occasions, when revolutionary decrees had to be enacted. The proposals were made by the signoria and carried in the ordinary way through the three councils. A constituent body of thirty was nominated by the signory. These were to appoint a ‘greater council’ of two hundred and ten members, afterwards enlarged to two hundred and fifty-eight, who were to act as a temporary _balia_, having power to legislate and to control the filling of the bags with the names of suitable candidates for office. In order to secure a wide distribution of influence, no family, except two specially named, was to have more than three members on the council. By a far more important provision the thirty were to nominate another forty, and with them were to constitute a permanent Council or Senate, known as the Seventy. The Seventy held office for life, and filled vacancies by co-optation. From among them were to be chosen the two important executive committees—the _Otto di Pratica_, who took the place of the occasional committees of eight or ten whom it had been usual to appoint in time of war, and the _Otto di Balia_, who superintended the police of the city. The institution of the Seventy did not abolish any of the old magistracies and councils; these still continued as a means of rewarding supporters and flattering men’s love of importance. But it placed side by side with them what Florence had not for a long time possessed, a permanent machinery of government, and thus supplied the stability, the want of which had been the chief cause which raised the Medici to their anomalous and ill-defined position in the state. It was inevitable that the Seventy, with its two standing committees, should gradually draw into its hands the real power which could never be effectually employed by officials who changed every two months.