In the Middle Ages authors like Pietro of Abano, Nicolas Oresme, and John Buridan argued that any phenomenon, in particular those which were usually believed to be supernatural or miraculous, could be explained according to natural principles as the result of hidden causes. A number of Renaissance thinkers also adopted this approach, including Pietro Pomponazzi. In his De incantationibus, Pomponazzi stated that men tend to consider phenomena wondrous when they are not able to identify their causes as the work of demons or miracles.  Pomponazzi attributed apparently miraculous events to the power of imagination, to psychological states or to the influence of the stars, since according to the Peripatetic paradigm the immutable first mover cannot have direct contact with the mutable sublunar world, and therefore moves through secondary causes. Nonetheless, despite his claim to speak purely secundum Aristotelem, Pomponazzi relied on a wider range of readings, including Marsilio Ficino. And in making these claims, Pomponazzi encroaches on very sensitive questions of religious faith. In his view, Christian miracles can be understood in the context of a sort of philosophy of history, founded on the horoscope of religions: when a religion begins, miracles occur, which are caused by starry influences, and when a religion declines, miracles disappear, because starry influences are weaker. This paradigm involved a rigid organization of the universe, which left little or no space for free will. Pomponazzi took this doctrine to its logical extreme in his De fato, a work in which he claimed to endorse Stoicism, while in reality exposing the determinism embedded in the Aristotelian doctrine of causes. Other Aristotelians who sought to avoid this determinism usually relied on the moderate position of Alexander of Aphrodisias, who Pomponazzi attacked in the first part of his treatise. While Pomponazzi reached these conclusions drawing on multiple sources, other authors, such as Gerardus Bucoldianus, Simone Porzio, and Ludovico Boccadiferro preferred to rely solely on Aristotle in order to explain wondrous events like cataclysms or the appearance of monstrous creatures, like those described by Ulisse Aldrovandi (1522–1605), who interpreted them as deviations from the course of nature, or Fortunio Liceti (1577–1657), who preferred to link the appearance of monsters to ingenious experiments of nature.