Comprehending the conditions under which tyranny might be successfully practised in the fifteenth century, Cosimo attached great value to this generosity. He used, in later life, to regret that 'he had not begun to spend money upon public works ten years earlier than he did.'[135] Every costly building that bore his name, each library he opened to the public, and all the donations lavished upon scholars served the double purpose of cementing the despotism of his house and of gratifying his personal enthusiasm for culture. Superstition mingled with these motives of the tyrant and the dilettante. Knowing that much of his wealth had been ill-gotten, he besought the Pope, Eugenius, to indicate a proper way of restitution. Eugenius advised him to spend 10,000 florins on the Convent of S. Marco. Thereupon Cosimo laid out considerably more than four times that sum, adding the famous Marcian Library, and treating the new foundation of the Osservanza, one of the Pope's favourite crotchets, with more than princely liberality.[136] [Footnote 135: Vespasiano, p. 257.] [Footnote 136: _Ibid._ p. 252. Cosimo ordered his clerks to honour all drafts presented with the signature of one of the chief brethren of the convent. 'Aveva ordinato al banco, che tutti i danari, che gli fussino tratti per polizza d'uno religioso de primi del convento, gli pagasse, e mettessegli a suo conto, e fussino che somma si volessino.'] Of his generosity to men of letters the most striking details are recorded. When Niccolo de' Niccoli ruined himself by buying books, Cosimo opened for him an unlimited credit with the Medicean bank. The cashiers received orders to honour the old scholar's drafts; and in this way Niccolo drew 500 ducats for his private needs.[137] Tommaso Parentucelli was treated with no less magnificence. As Bishop of Bologna, soon after his patron Albergati's death, he found himself with very meagre revenues and no immediate prospect of preferment. Yet the expenses of his station were considerable, and he had occasion to request a loan from the Medici. Cosimo issued a circular letter to his correspondents, engaging them to supply Tommaso with what sums of money he might want.[138] When the Bishop of Bologna assumed the tiara, with the name of Nicholas V., he rewarded Cosimo by making him his banker; and the Jubilee bringing 100,000 ducats into the Papal treasury, the obligation was repaid a hundredfold.[139] [Footnote 137: Vespasiano, pp. 264, 475.] [Footnote 138: Vespasiano, pp. 29, 264.] [Footnote 139: _Ibid._ pp. 34, 265.]