Nicolaus Copernicus surviving primary documents on the early years of Copernicus's childhood and education. Copernicus biographers assume that Watzenrode first sent young Copernicus to St. John's School, at Toruń, where he himself had been a master. Later, according to Armitage, the boy attended the Cathedral School at Włocławek, up the Vistula River from Toruń, which prepared pupils for entrance to the University of Kraków, Watzenrode's alma mater in Poland's capital. In the winter semester of 1491–92 Copernicus, as "Nicolaus Nicolai de Thuronia", matriculated together with his brother Andrew at the University of Kraków (now Jagiellonian University). Copernicus began his studies in the
Nicolaus Copernicus (Kulm), to be delivered to Rheticus for printing by the German printer Johannes Petreius at Nuremberg ("Nürnberg"), Germany. While Rheticus initially supervised the printing, he had to leave Nuremberg before it was completed, and he handed over the task of supervising the rest of the printing to a Lutheran theologian, Andreas Osiander. Osiander added an unauthorised and unsigned preface, defending Copernicus' work against those who might be offended by its novel hypotheses. He argued that "different hypotheses are sometimes offered for one and the same motion [and therefore] the astronomer will take as his first choice that hypothesis which is