 Two questions are intensively discussed by modern specialists. Firstly, to what extent is the attribution of a mechanistic approach to Kepler justified? Secondly, how should one determine his place in the history of sciences, especially in the field of optics: do the main lines of thought in Kepler’s optics indicate a continuity or rather a rupture with tradition? There are well–grounded arguments for different positions on both questions. For Crombie (1967, 1991) and Straker, Kepler develops a mechanical approach, which can be particularly appreciated in his explanation of vision using the model of the camera obscura. Besides this, Straker stresses that Kepler’s basic mechanicism is also powerfully assisted by his conception of light as a non-active, passive entity. In addition, the concept of motion and the explanations using the model of the balance are indicative of a commitment to mechanicism (Straker 1970, pp. 502–3). On the contrary, Lindberg (1976a), who supports the “continuity side” of the dispute, has quite convincingly showed that, for Kepler, light has a constructive and active function in the universe, not only in optics but also in astrology, astronomy, and natural philosophy (for Kepler’s criticism of the medieval tradition see also Chen-Morris / Unguru, 2001).