The subject of preaching, and its practice by the bishops of the fifteenth and early sixteenth centuries, is one which demonstrated a separation of theory and practice. The centrality of the ministry of the Word in the exercise of episcopal functions was frequently acknowledged in theory and more frequently disregarded in practice. Many ecclesiastical Reformers complained of clergy, and bishops in particular, who failed to exercise a preaching ministry. The revival of the study of the sacred languages and a desire to return to the sources of revelation and of secular literature, characteristics of that intellectual movement which advocated what was known as the new learning, only served to make this omission more apparent. When Erasmus published his new edition of the New Testament in Greek and Latin in 1516, his opinion as to the centrality of the preaching of the word was clearly set out in the opening verse of St John's Gospel. His choice of the word Sermo to translate the Greek Logos, rather than Verbum, was most significant. Not only did he choose to use a word which signified something active, the Word as spoken, as preached, he also made this alteration in a verse familiar to any priest from its liturgical usage at the end of the ordinary of the Mass. Marsilius of Padua, the medieval political thinker whose writings were known in England even before the publication of a partial English translation of his Defensor pacis in 1535, taught in that work that the preaching of the divine law, and the administration of the sacraments in accordance with it, were of the essence of the priesthood.