The Protestant Reformation and rise of modernity in the early 16th century entailed the start of a series of changes in the "Corpus Christianum". Martin Luther challenged the Catholic Church with his Ninety-five Theses, generally accepted as the beginning of the Reformation, a Christian reform movement in Europe, though precursors such as Jan Hus predate him. The Protestant movement of the 16th century occurred under the protection of the Electorate of Saxony, an independent hereditary electorate of the Holy Roman Empire. The Elector Frederick III established a university at Wittenberg in 1502. The Augustinian monk Martin Luther became professor of philosophy there in 1508. At the same time, he became one of the preachers at the castle church of Wittenberg.