By the end of the sixteenth century, many Jesuit colleges had become centers of excellence all over Europe for such disciplines as mathematics, astronomy, hydraulics, and mechanics. Not a few members of the order provided influential contributions to science: in the case of the study of waters, the inquisitive eye of Jesuits took part in the long-standing debate on the origin of springs.
These attempts to harmonize religion, experimentalism, and philosophy, though carried out within the rigorous theo-retical framework imposed by the Counter-Reformation, gave rise to a number of significant and ingenious interpretations of hydrogeological phenomena: and a crucial role was played by the use of iconography. Images became essential tools to ease the comprehension of refined theoretical models, made even more tortuous by the need to conform with Catholic doctrine – and, therefore, with two unescapable hurdles: the non-existence of void, and geocentrism. This approach re-quired Jesuits to focus on the same topics handled by their enemies; and, consequently, led them to interact with the very theories they opposed.