The "Impiety' of Kepler's shift from mathematical astronomy to celestial physics

Johannes Kepler, the imperial mathematician, met severe philosophical and theological criticism against his seminal work in celestial physics. Kepler's physics infringed on widely accepted disciplinary separations and metaphysical principles of astronomy. First and foremost, his approach invalidated the traditional distinction between mathematical astronomy representing heavenly phenomena and the natural philosophy explaining their causes. Moreover, he abandoned the Aristotelian assumption that the heavens, owing to their perfection and closeness to the divine, follow physical laws which are different than those ruling the terrestrial (or sublunary) realm. The perceived contrast between Kepler's theory and the astronomical tradition is particularly true for his elliptical orbits and the law of areas. Kepler's vision of a celestial physics looked suspicious if not impious to the researchers, because it downplayed a mathematical discipline dealing with perfect bodies to the rank of a physical discipline blemished by the material imperfection of the lowest realms in nature.