In 1668 B. Radziwiłł, a representative of a prominent magnate family from the Grand Duchy of Lithuania, donated his book collection to Frederick William, Elector of Brandenburg, and obliged him to donate them to the electoral library in Königsberg. Radziwiłł, who was an influential politician and military officer, was a patron of culture and science. His donation was intended to supply the library with books that were unique and sometimes first editions. The book collection consisted of works on a wide variety of subjects, including the humanities, theology, law, history, philosophy, geography, astronomy, mathematics and physics, which reflected the wide interests and education of Radziwiłł himself. Many of the items listed in the inventory were most likely acquired by the prince during his many years abroad. Of the 449 items included in the inventory compiled by M. S. Grabe, 39 have survived to our times and are housed in the Library of the Nicolaus Copernicus University in Toruń.