In the autumn of 1517, he was in Wittenberg, met with Martin Luther, and became involved in the great discussions which preceded the posting of Luther's 95 Theses. He attended lectures at the university there, and was exposed to Luther's ideas as well as other ideas originating with the humanists, among whom was Andreas Bodenstein von Karlstadt, who later became a radical opponent of Luther. Müntzer did not remain in Wittenberg for long, and was reported in various other locations in Thuringia and Franconia. He continued to be paid for his position at Braunschweig until early 1519, when he turned up in the town of Jüterbog, north-east of Wittenberg, where he had been asked to stand in for the preacher Franz Günther. Günther had already been preaching the reformed gospel, but had found himself attacked by the local Franciscans; requesting leave of absence, he left the scene and Müntzer was sent in. The latter picked up where Günther had left off. Before long, the local ecclesiastics were complaining bitterly about Müntzer's heretical "articles" which challenged both church teaching and church institutions. By this time, Müntzer was not simply following Luther's teachings; he had already begun to study the works of the mystics Henry Suso and Johannes Tauler, was seriously wondering about the possibility of enlightenment through dreams and visions, had thoroughly explored the early history of the Christian church, and was in correspondence with other radical reformers such as Karlstadt.