Before his death in 1464 Cosimo de' Medici had succeeded in rendering his family necessary to the State of Florence. Though thwarted by ambitious rivals and hampered by the intrigues of the party he had formed to rule the commonwealth, Cosimo contrived so to complicate the public finances with his own banking business, and so to bind the leading burghers to himself by various obligations, that, while he in no way affected the style of a despot, Florence belonged to his house more surely than Bologna to the Bentivogli. For the continuation of this authority, based on intrigue and cemented by corruption, it was absolutely needful that the spirit of Cosimo should survive in his successors. A single false move, by unmasking the tyranny so carefully veiled, by offending the republican vanities of the Florentines, or by employing force where everything had hitherto been gained by craft, would at this epoch have destroyed the prospects of the Medicean family. So true it is that the history of this age in Italy is not the history of commonwealths so much as the history of individualities, of men. The principles reduced to rule by Machiavelli in his essay on the Prince may be studied in the lives of fifteenth-century adventurers, who, like Cesare Borgia, discerned the necessity of using violence for special ends, or, like the Medici, perceived that sovereignty could be better grasped by a hand gloved with velvet than mailed in steel. The Medici of both branches displayed through eight successive generations, in their general line of policy, in the disasters that attended their divergence from it, and in the means they used to rehabilitate their influence, the action of what Balzac calls _l'homme politique_, with striking clearness to the philosophic student.