Nicolaus Copernicus wrote his most important work, De revolutionibus or bium coelestium, in stages. The manuscript of this work, published in 1543 in Nuremberg, has survived. Immediately after the death of Copernicus, the manuscript of De revolutionibus… was in the possession of Bishop Tiedmann Giese. The next owner of the manuscript was Joachim Retyk, who lived in Cracow in the years 1554–1574. After the death of Rheticus, the manuscript of De revolutionibus… was handed over to Valentin Otho, a collaborator of Rhe ticus and later a professor at Wittenberg and Heidelberg. In Heidelberg, the manuscript was bound and became the property of Professor Jakub Christ mann. In 1614, Jan Amos Komensky, as a Heidelberg student, bought the Copernicus’s manuscript from the widow of J. Christann. Under unknown circumstances, this manuscript was placed in the library of Otto von Nostitz in Jawor, Silesia, before 1665, and then in the library of his family in Prague. In 1945, it was taken over by the Czechoslovak state and transferred to the Li brary of the National Museum in Prague. In 1956, the government of Czecho slovakia donated the manuscript of De revolutionibus… to Poland. Since that year, it has been the property of the Jagiellonian University, Copernicus’s Alma Maer, and is now part of the collections of the Jagiellonian Library.