Arnold Geulincx (; 31 January 1624 – November 1669), also known by his pseudonym Philaretus, was a Flemish philosopher, metaphysician, and logician. He was one of the followers of René Descartes who tried to work out more detailed versions of a generally Cartesian philosophy. Samuel Beckett cited Geulincx as a key influence and interlocutor because of Geulincx's emphasis on the powerlessness and ignorance of the human condition. Life Geulincx was born in Antwerp. He studied philosophy and theology at the University of Leuven and was made professor of philosophy there in 1646. He lost his post in 1658, possibly for religious reasons, or (as has been suggested) a combination of unpopular views and his marriage in that year. In September 1658, Geulincx became a medical doctor. He then moved north to the University of Leiden and converted to Calvinism. Initially he gave private lessons in philosophy. He was appointed reader in logic there in 1662 and professor by special appointment in 1665. Until 1662, Geulincx lived in poverty. He died in Leiden in November 1669, leaving most of his works, all written in Latin, to be published after his death. They were edited by Cornelis Bontekoe. Reputation Despite Geulincx's thesis that God cannot act without an instrumentality of variety, he was strongly attacked in the early eighteenth century, for example, by Ruardus Andala and Carolus Tuinman, as a Spinozist. This criticism had originated from Christian Thomasius in 1710. The attack from Andala was on behalf of the "true" Cartesians, classing Geulincx as pernicious, with Burchardus de Volder, Jean LeClerc, Frederik van Leenhof, Pontiaan van Hattem and Willem Deurhoff. Geulincx was also attacked by the Pietist Joachim Lange, as part of a campaign against Christian Wolff; and regarded with Pierre Bayle as insidiously anti-Christian by Johann Franz Buddeus. Philosophy Geulincx summarized his philosophy in the phrase "" ("it exists, therefore it is so"). He believed in a "pre-established harmony" as a solution to the mind–body problem, dying 25 years before Leibniz's better-remembered formulation of the idea. In Leibniz's philosophy, the doctrine of pre-established harmony was linked with optimism, the notion of this world as the "best of all possible worlds". But Geulincx made no such linkage. The occasionalism of Geulincx is ethical rather than cosmological in its inception. The first tract of his Ethics is a study of what in his terms are the cardinal virtues. Virtue according to Geulincx is