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Abstract

Theodorus Graminaeus, a mathematician in the service of the Counter-Reformation

Theodorus Graminaeus (ca. 1540-1596) offers an example of the fluid status of mathematics and its practitioners in the early modern period. Born at Roermond, Graminaeus studied at Cologne, where he became a professor of mathematics in 1566. As a professor, Graminaeus also acted as printer and publisher of mathematical, religious and other works. In 1575 he obtained a licentiate in law. Around the same time, he became tutor of Johann Wilhelm, crown prince to the United Duchies of Jülich, Cleves and Berg. In 1582, he left his position at the university of Cologne and appears to have entered the service of Johann Wilhelm full time. After the latter’s succession as duke (1592), Graminaeus got an administrative position in the duchy of Berg.

Graminaeus wrote a dozen works on a variety of subjects, including the calendar, comets, the Antichrist, witches, and publicity for the dukes of Cleves. He did not aim at exactness and objectivity. Even his mathematical works bear the stamp of his religious beliefs and embody religious and political values. Tycho Brahe (who refuted Graminaeus’s work on the nova of 1572 at some length) already felt that they lacked rigour. Graminaeus felt he lived in a very dark age. He had witnessed the religious troubles at his birthplace, Roermond, in 1566-1567 and since that time abhorred Protestantism. In his work, he tried to read the signs of the time by finding patterns in world history based on astrological models and ancient prophecies. (In this, he appears not to have been unique among Catholics at Cologne.) At the court of Cleves, he put himself decidedly on the side of the Roman-Catholic faction. As the Counter- Reformation, led by the Jesuits, gained momentum in the United Duchies, his expectations became somewhat less gloomy.

Keywords: Graminaeus, Contra-Reformation, Mathematics