According to his own account, Descartes had gone ‘to war’ with the French Jesuits in 1640. While that controversy was still active, he opened hostilities on a second front two years later with the rector of Utrecht University, Gisbertus Voetius (1589–1676) and, eventually, with the Utrecht city council. At the height of this controversy, Regius was described in a student's Latin rhyme as the ‘French liar's monkey’. The ‘French liar’ himself, Descartes, was characterized by a somewhat reluctant critic as follows: ‘The man lacks all modesty, is proud, supercilious, scandalous and quarrelsome.’ The unusually sharp language used by both sides, even when judged by the standards that prevailed at that time, shows the depth of the rift involved.

As usual, Descartes offered a benign and self-serving interpretation of his motivation. ‘All I ask for is peace … but I see that, to obtain it, I have to wage war a little.’ It is hardly credible however that, while living in comparative solitude in a rented castle at Endegeest (in the province of Holland), he had to engage in public controversy with influential Dutch theologians in another province (Utrecht) in order to protect his tranquillity. It is much more likely that he blundered into this theological and political minefield by making careless comments about Voetius in an appendix to the second edition of the Meditations, which was published in Amsterdam.