The impulse which proceeded from Petrarch and Boccaccio, superficial as was their own acquaintance with Greek, was powerful, but did not tell immediately on their contemporaries;[453] on the other hand, the study of Greek literature died out about the year 1520[454] with the last of the colony of learned Greek exiles, and it was a singular piece of fortune that northerners like Agricola, Reuchlin, Erasmus, the Stephani, and Budæus had meanwhile made themselves masters of the language. That colony had begun with Manuel Chrysoloras and his relation John, and with George of Trebizond. Then followed, about and after the time of the conquest of Constantinople, John Argyropulos, Theodore Gaza, Demetrios Chalcondylas, who brought up his sons Theophilos and Basilios to be excellent Hellenists, Andronikos Kallistos, Marcos Musuros and the family of the Lascaris, not to mention others. But after the subjection of Greece by the Turks was completed, the succession of scholars was maintained only by the sons of the fugitives and perhaps here and there by some Candian or Cyprian refugee. That the decay of Hellenistic studies began about the time of the death of Leo X. was owing partly to a general change of intellectual attitude,[455] and to a certain satiety of classical influences which now made itself felt; but its coincidence with the death of the Greek fugitives was not wholly a matter of accident. The study of Greek among the Italians appears, if we take the year 1500 as our standard, to have been pursued with extraordinary zeal. The youths of that day learned to speak the language, and half a century later, like the Popes Paul III. and Paul IV., they could still do so in their old age.[456] But this sort of mastery of the study presupposes intercourse with native Greeks. Besides Florence, Rome and Padua nearly always maintained paid teachers of Greek, and Verona, Ferrara, Venice, Perugia, Pavia and other cities occasional teachers.[457] Hellenistic studies owed a priceless debt to the press of Aldo Manucci at Venice, where the most important and voluminous writers were for the first time printed in the original. Aldo ventured his all in the enterprise; he was an editor and publisher whose like the world has rarely seen.[458]