Abstract

Johannes Jessenius published the treatise on Causes of Sympathy and Antipathy in 1599 which was defended by his student and disciple Daniel Sennert. This disquisition provides interesting material with respect to the concept of natural philosophy and its development in both Jessenius and Sennert. Although Jessenius proclaims that he deals with the question of sympathy and antipathy generally in the Aristotelian manner, he simultaneously indicates the inspiration and main source of his disquisition, these having been lectures held by the Paracelsian Tycho de Brahe. Jessenius, with the help of a distinction between occult and manifest qualities, connected in his disquisition the principles of Aristotelian naturalism with the Paracelsian notion of correspondences between the higher and lower world. Sennert in his later works finds the theory of sympathy, based on analogies or on the doctrine of occult qualities, incompatible with Aristotelian scientific methodology and thereby implicitly demonstrates the inconsistencies in Jessenius's disquisition.