In the early 1540ies G.J. Rheticus wrote an anonymous treatise entitled both Epistola de
Terrae Motu and Dissertatio de Hypoth[esibus] Astron[omiae] Copernicanae. In this
letter he discusses why proclaiming the motion of the earth does not need to be
considered as an impious act incompatible with the words of Holy Scripture. Based on
an analysis of authorities mentioned by the author in this letter, I conclude that
Rheticus’ strategy on the one hand consists in playing down the importance of the
traditional Aristotelian-Ptolemaic notions on the universe in the field of astronomy and
by emphasizing the indirect character of Biblical authority in these matters. On the other
hand, he claims the absolute, immediate authority of mathematics in astronomy by
which he consequently challenges the traditional medieval hierarchy of sciences.
Rheticus considers the achievements of Copernicus to be part of divine providence.