Johannes Kepler, after moving through grammar school,…
April 1594 CE
Johannes Kepler, after moving through grammar school, Latin school, and lower and higher seminary in the Württemberg state-run Protestant education system, had in 1589 begun attending the University of Tübingen, where he studied philosophy under Vitus Müller and theology under Jacob Heerbrand (a student of Philipp Melanchthon at Wittenberg) who also taught Michael Maestlin while he was a student, until he became Chancellor at Tübingen in 1590.
He proved himself to be a superb mathematician and earned a reputation as a skillful astrologer, casting horoscopes for fellow students.
Under the instruction of Maestlin, Tübingen's professor of mathematics from 1583, he had learned both the Ptolemaic system and the Copernican system of planetary motion, becoming a Copernican.
In a student disputation, he had defended heliocentrism from both a theoretical and theological perspective, maintaining that the Sun was the principal source of motive power in the universe.
Despite his desire to become a minister, near the end of his studies Kepler had been recommended for a position as teacher of mathematics and astronomy at the Protestant school in Graz, Austria (later the University of Graz).
He accepts the position in April 1594, at the age of twenty-three.