Luther, directly opposing the naturalism of Aristotelian natural philosophy, held that unusual events were often worked directly by either God or the devil, not by natural forces. His ideas were taken up and defended in a more philosophical way by authors like Joachim Camerarius and Caspar Peucer. At the university of Wittenberg, they deeply influenced the teaching of natural philosophy. The field most affected was meteorology (traditionally the explanation of Aristotle's Meteorologia), which obtained a prominent place. Meteorological text-books emphasised the final causes of the phenomena they described; not just their place in the general economy of nature, but also their function in warning and punishing sinners. Moreover, they emphasised that many phenomena people had observed were overstepping their natural limits and as such could not be explained naturally. The text-books, however, did not fully break away from the tradition of commentaries to Aristotle's Meteorologia, which emphasised naturalism. Only topics not discussed in this tradition were unambiguously explained as miraculous.