Celestial Spheres in Fifteenth-Century Cracow Astronomy and Natural Philosophy
SCIREA Journal of Sociology http://www.scirea.org/journal/Sociology June 23, 2021 Volume 5, Issue 4, August 2021 Celestial Spheres in fifteenth-Century Cracow Astronomy and Natural Philosophy ANDRÉ GODDU Emeritus Professor of Astronomy and Physics, Stonehill College, Easton, Massachusetts, USA Abstract Medieval astronomers adopted the celestial spheres of Aristotelian cosmology, and combined them with Ptolemy’s geometrical models, unaware directly that Ptolemy himself had interpreted the mathematical models of deferents and epicycles as spheres, and also as the entire physical orbs in which planets are moved. This essay focuses on discussions and developments of the tradition of celestial spheres and geometrical models at the University of Cracow in the fifteenth century. After tracing the original contributions of astronomers and philosophers, the essay turns in particular to the commentary of Albert of Brudzewo on the most developed version of the spherical astronomy of the fifteenth century, Georg Peurbach’s Theoricae novae planetarum. Albert’s critique of that treatise along with his solutions to the problems that he identified set the stage for Nicholas Copernicus’s adoption of celestial spheres and his innovative solutions for the reform of Ptolemaic astronomy. 176 Keywords: celestial spheres, Aristotle, Ptolemy, University of Cracow, Georg Peurbach, Albert of Brudzewo, Nicholas Copernicus Introduction “About what we cannot speak we must be silent.” Ludwig Wittgenstein’s famous dictum distinguished between what can be said and what can be shown. The aim of his book, Tractatus Logico-Philosophicus, was to set a limit to the expression of thoughts. Only in language can the limit be set, and what lies on the other side of the limit is nonsense.1 Of course, exposing nonsense sometimes takes centuries.
[Show full text]