The chief benefit conferred by Cosimo de' Medici on learning was the accumulation and the housing of large public libraries. During his exile (Oct. 3, 1433--Oct. 1, 1434) he built the Library of S. Giorgio Maggiore at Venice, and after his return to Florence he formed three separate collections of MSS. While the hall of the Library of S. Marco was in process of construction, Niccolo de' Niccoli died, in 1437, bequeathing his 800 MSS., valued at 6,000 golden florins, to sixteen trustees. Among these were Cosimo and Lorenzo de' Medici, Ambrogio Traversari, Lionardo Bruni, Carlo Marsuppini, Poggio Bracciolini, Giannozzo Manetti, and Franco Sacchetti. At the same time the estate of Niccolo was compromised by heavy debts. These debts Cosimo cancelled, obtaining in exchange the right to dispose of the library. In 1441 the hall of the convent was finished. Four hundred of Niccolo's MSS. were placed there, with this inscription upon each: _Ex hereditate doctissimi viri Nicolai de Nicolis de Florentiâ._ Tommaso Parentucelli made a catalogue at Cosimo's request, in which he not only noted the titles of Niccoli's books, but also marked the names of others wanting to complete the collection. This catalogue afterwards served as a guide to the founders of the libraries of Fiesole, Urbino, and Pesaro, and was, says Vespasiano, indispensable to book-collectors.[140] Of the remaining 400 volumes Cosimo kept some for his own (the Medicean) library, and some he gave to friends. At the same time he spared no pains in adding to the Marcian collection. His agents received instructions to buy codices, while Vespasiano and Fra Giuliano Lapaccini were employed in copying rare MSS. As soon as Cosimo had finished building the Abbey of Fiesole, he set about providing this also with a library suited to the wants of learned ecclesiastics. Of the method he pursued, Vespasiano, who acted as his agent, has transmitted the following account:[141]--'One day, when I was in his room, he said to me, "What plan can you recommend for the formation of this library?" I answered that to buy the books would be impossible, since they could not be purchased. "What, then, do you propose?" he added. I told him that they must be copied. He then asked if I would undertake the business. I replied that I was willing. He bade me begin at my leisure, saying that he left all to me; and for the monies wanted day by day, he ordered that Don Arcangelo, at that time prior of the monastery, should draw cheques upon his bank, which should be honoured. After beginning the collection, since it was his will that it should be finished with all speed possible, and money was not lacking, I soon engaged forty-five copyists, and in twenty-two months provided two hundred volumes, following the admirable list furnished by Pope Nicholas V.' The two libraries thus formed by Cosimo for the Convents of S. Marco and Fiesole, together with his own private collections, constitute the oldest portion of the present