with the inauguration of two popes in 1378, Wycliffe began publicly to identify the Bible, and not the pope, as the supreme source of spiritual authority. The papacy, he argued, was merely a human invention, whereas the Bible authoritatively determined the validity of all religious beliefs and practices. On this basis he rejected the highly philosophical doctrine of transubstantiation. In a few short years such talk had got Oxford—and the whole country—seething. Wycliffe had to retire, which he did,