The humanists of the fourteenth century ordinarily knew no Greek. Some knowledge of that language lingered in the West all through the Middle Ages, but we hear of no one attempting to read Plato, Demosthenes, Æschylus, or even Homer, and these authors were scarcely ever found in the libraries. Petrarch and his followers were naturally much interested in the constant references to Greek literature which occur in Cicero and Horace, both of whom freely recognized their debt to Athens. Shortly after Petrarch's death the city of Florence called to its university a professor of Greek, Chrysoloras from Constantinople. [Sidenote: Revival of Greek studies in Italy.] [Sidenote: Chrysoloras in Florence.] A young Florentine law student, Leonardo Bruni, tells us of a dialogue which he had with himself when he heard of the coming of Chrysoloras. "Art thou not neglecting thy best interests if thou failest now to get an insight into Homer, Plato, Demosthenes, and the other great poets, philosophers, and orators of whom they are telling such wonderful things? Thou, too, mightest commune with them and imbue thyself with their wisdom. Wouldst thou let the golden opportunity slip? For seven hundred years no one in Italy has known Greek literature, and yet we agree that all language comes from the Greeks. How greatly would familiarity with that language advantage thee in promoting thy knowledge and in the mere increase of thy pleasure? There are teachers of Roman law to be found everywhere, and thou wilt never want an opportunity to continue that study, but there is but one teacher of Greek, and if he escapes thee there will be no one from whom thou canst learn." [Sidenote: The knowledge of Greek becomes common in Europe.] Many students took advantage of the opportunity to study Greek, and Chrysoloras prepared the first modern Greek grammar for their use. Before long the Greek classics became as well known as the Latin. Italians even went to Constantinople to learn the language; and the diplomatic negotiations which the Eastern Church carried on with the Western, with the hope of gaining help against the Turks, brought some Greek scholars to Italy. In 1423 an Italian scholar arrived at Venice with no less than two hundred and thirty-eight Greek books, thus transplanting a whole literature to a new and fruitful soil.[226] Greek as well as Latin books were carefully copied and edited, and beautiful libraries were established by the Medici, the duke of Urbino, and Pope Nicholas V, who founded the great library of the Vatican,[227] still one of the most important collections of books in the world. [Sidenote: Advantages of printing with movable types.]