Johannes Kepler (Dec 27, 1571 - Nov 15, 1630) was a German astronomer, astrologer, and mathematician. A key figure in the 17th century scientific revolution, he is best known for his Laws of Planetary Motion, based on his works Astronomia Nova, Harmonices Mundi, and Epitome of Copernican Astronomy. (These works also provided one of the foundations for Englishman Isaac Newton’s theory of universal gravitation.) During his career, he was a math teacher at a seminary school in Graz, where he became an associate of Prince Hans Ulrich von Eggenberg. Later he became an assistant to Danish astronomer Tycho Brahe, and eventually the imperial mathematician to Emperor Rudolf II and his successors Matthias and Ferdinand II. He was also a math teacher in Linz, and an adviser to General Wallenstein. He did fundamental work in the field of optics and invented an improved version of the refracting telescope (Keplerian Telescope). He lived in an era when there was no clear distinction between Astronomy and Astrology, but there was a strong division between Astronomy (a branch of Mathematics within the Liberal Arts) and Physics (a branch of Natural Philosophy). Kepler also incorporated religious arguments and reasoning into his work, motivated by the religious conviction and belief that God had created the world according to an intelligible plan that is accessible through the natural light of reason. He described his new Astronomy as “Celestial Physics”, “an excursion into Aristotle’s Metaphysics”, and “a supplement to Aristotle’s On the Heavens”, transforming the ancient tradition of Physical Cosmology by treating astronomy as part of a universal mathematical physics. Read more here.