Martin Luther, John Calvin, and Ulrich Zwingli are considered Magisterial Reformers because their reform movements were supported by ruling authorities or "magistrates". Frederick the Wise not only supported Luther, who was a professor at the university he founded, but also protected him by hiding Luther in Wartburg Castle in Eisenach. Zwingli and Calvin were supported by the city councils in Zurich and Geneva. Since the term "magister" also means "teacher", the Magisterial Reformation is also characterized by an emphasis on the authority of a teacher. This is made evident in the prominence of Luther, Calvin, and Zwingli as leaders of the reform movements in their respective areas of ministry. Because of their authority, they were often criticized by Radical Reformers as being too much like the Roman Popes. For example, Radical Reformer Andreas von Bodenstein Karlstadt referred to the Wittenberg theologians as the "new papists".