  From early in his correspondence with Mersenne, Descartes showed a concern to avoid becoming embroiled in theological controversy or earning the enmity of church authorities (1:85–6, 150, 271).  Nonetheless, he was drawn into theological controversy with Calvinist theologians in the Netherlands. In the latter 1630s,  Henry le Roy (1598–1679), or Regius,  a professor of medicine in Utrecht, taught Descartes' system of natural philosophy. Already by 1640, Gisbert Voetius (1589–1676),  a theologian at Utrecht, expressed his displeasure over this to Mersenne (3:230). Controversy brewed, at first between Regius and Voetius, with Descartes advising the former. Voetius, who was rector of the University, convinced the faculty senate to condemn Descartes' philosophy in 1642. He and his colleagues published two works (in 1642 and 1643) attacking Descartes' philosophy, to which Descartes himself responded by publishing a Letter to Voetius (1643). The controversy simmered through the mid-1640s. Descartes eventually had a falling out with Regius, who published a broadsheet or manifesto that deviated from Descartes' theory of the  human mind. Descartes replied with his Comments on a Certain Broadsheet (1648).