In the 1520s during the Protestant Reformation, the city, under the political guidance of Jacob Sturm von Sturmeck and the spiritual guidance of Martin Bucer embraced the religious teachings of Martin Luther. Their adherents established a Gymnasium, headed by Johannes Sturm, made into a University in the following century. The city first followed the Tetrapolitan Confession, and then the Augsburg Confession. Protestant iconoclasm caused much destruction to churches and cloisters, notwithstanding that Luther himself opposed such a practice. Strasbourg was a centre of humanist scholarship and early book-printing in the Holy Roman Empire, and its intellectual and political influence contributed much to the establishment of Protestantism as an accepted denomination in the southwest of Germany. (John Calvin spent several years as a political refugee in the city). The Strasbourg Councillor Sturm and guildmaster Matthias represented the city at the Imperial Diet of Speyer (1529), where their protest led to the schism of the Catholic Church and the evolution of Protestantism. Together with four other free cities, Strasbourg presented the confessio tetrapolitana as its Protestant book of faith at the Imperial Diet of Augsburg in 1530, where the slightly different Augsburg Confession was also handed over to Charles V, Holy Roman Emperor.