The phenomenal spread of the Reformation in Poland was due, first of all, to certain social causes. Among these probably the most potent were the Renaissance, the art of printing, the influence of foreign universities, particularly those of Germany and Switzerland, religious toleration in Poland in the sixteenth century, and the fact that the new ideas were accepted, championed, and maintained by the upper classes of the population, thus giving the Reformation movement a certain prestige, popularity, and much needed moral and material support. As in the West, so also in Poland the way for the religious Reformation was prepared in a large measure by the Renaissance. The new learning, together with the new temper of mind resulting therefrom, reached Poland early in the fifteenth century, won many enthusiastic followers among the educated nobility and even among the higher clergy, and exerted a powerful influence over the minds of the upper classes in the nation throughout the sixteenth century. Many of the Polish bishops were ardent admirers of Erasmus, among whom were Tomicki, Maciejowski, Zebrzydowski, Padniewski, and Myszkowski. Their episcopal courts as well as those of some of the Polish magnates, including that of Hetman Jan Tarnowski, were centres of humanistic culture.[181] The most notable representatives of the new temper of mind and exponents of the new ideas were John Ostrorog, who died in 1501, John Łaski, known also as John a Lasco, and Andrew Frycz Modrzewski; the first living and writing in the fifteenth and the second two in the sixteenth century. In his Monumentum pro reipublicae ordinatione, published in 1456, John Ostrorog opposed the Polish king’s humble submissiveness to the pope, the payment of annates, the proclamation in the country of papal jubilees and indulgences for the purpose of collecting money, contended for the separation of the Polish church from Rome, and advocated state control of clerical education.[182] John Łaski (1499-1560), nephew of the primate of the same name, was the most ardent and conspicuous Polish humanist and patron of humanists before his acceptance of the Reformation and his break with the established church. He had spent some time with Erasmus at Basel, purchased the great scholar’s wonderful library, the use of which, however, he left to his master until his death, and on his return home in 1526 became a zealous promoter of humanistic studies in his own country and the most distinguished patron of a number of young Polish humanists, among whom were Modrzewski, Andrew Trzycieski, Rullus, Hosius; the Silesians, Pyrser, Lang, Ephorinus, Frederick of Freistadt; the Hungarian Antoninus, the Frenchman Aignan Bourgoin, known also as Anian, and the Englishman Coxe.[183]