He frequently considered fire as the Firmament that sat in between air and drinking water in the heavens. In De Meteoris, Paracelsus wrote that the firmament is the heavens. As a medical doctor of the early 16th century, Paracelsus held a natural affinity with the Hermetic, Neoplatonic, and Pythagorean philosophies central to the Renaissance, a planet-watch exemplified by Marsilio Ficino and Pico della Mirandola.