that time Moretus had acquired the title of Master in Liberal Arts and Philosophy, but it is not clear when or where he obtained the title. He returned to Prague at the end of 1634. Moretus was the author of the first mathematical dissertation ever defended in the College of St. Clement (the 'Clementinum') in Prague. The dissertation was entitled Propositiones mathematicae de celeri et tardo, naturae et armorum and was defended by Moretus in 1633 or 1635. The present whereabouts of the manuscript of the dissertation is not known. From 1642 to 1645, Theodorus left his teaching post as he was sent as a preacher and missionary to the home that the Jesuits owned in Brzezenica, a small town in Galicia. In 1646 he was sent back to Prague as a professor, initially, of Holy Scripture and no longer of mathematics. He also was appointed to the office of councilor of the provincial council of Bohemia. Moretus left Prague in 1653, and on 19 August of the same year, he took over the rectorate of the college of Klatovy. It was a difficult task as the little college had fallen into ruin and the new rector had to rebuild it with funds he had to find himself. He managed the college for three years. He spent the year 1657 at Neisse (now Nysa, in Poland), occupied in various apostolic ministries. From there he went to Głogów in 1658. The same year he embarked on a long journey through Bohemia, Moravia and Austria. In 1660 Moretus was for the first time attached to the College of Breslau, where he joined the apostolic ministry for the teaching of mathematics. He remained in this college for two years. He spent the year 1662 at Kłodzko but soon returned to Breslau, probably as early as 1663. It was during his stay at Kłodzko that he published his Principatus incomparabilis primi filii hominis messiae et primae parentis Matris Virginis : in conceptione illius immaculata exhibitus in Cologne. The Principatus is a work of both theology and piety and was intended to defend the thesis of the Immaculate Conception. Moretus submitted in 1664 a paper entitled Propositiones mathematicas ex harmonica de Soni Magnitude, which was later published. This treatise provided a mathematical analysis of the harmony of sounds. The work shows Moretus to be a follower of Pythagoras who was much attached to the old