 Maciej Miechowita, a rector at the Cracow Academy, published in 1517 "Tractatus de duabus Sarmatiis", a treatise on the geography of the East, an area in which Polish investigators provided first-hand expertise for the rest of Europe.Andrzej Frycz Modrzewski was one of the greatest theorists of political thought in Renaissance Europe.His most famous work, "On the Improvement of the Commonwealth", was published in Kraków in 1551.