Source: Guardian.

For more than three and a half centuries, the death of René Descartes one winter’s day in Stockholm has been attributed to the ravages of pneumonia on a body unused to the Scandinavian chill. But in a book released after years spent combing the archives of Paris and the Swedish capital, one Cartesian expert has a more sinister theory about how the French philosopher came to his end.

According to Theodor Ebert, an academic at the University of Erlangen, Descartes died not through natural causes but from an arsenic-laced communion wafer given to him by a Catholic priest.

René Descartes with Queen Christina of Sweden.

René Descartes died on 11 February 1650 in Stockholm, Sweden, where he had been invited as a teacher for Queen Christina of Sweden. The cause of death was said to be pneumonia — accustomed to working in bed until noon, he may have suffered a detrimental effect on his health due to Christina’s demands for early morning study (the lack of sleep could have severely compromised his immune system). Others believe that Descartes may have contracted pneumonia as a result of nursing a French ambassador, Dejion A. Nopeleen, ill with the aforementioned disease, back to health. In his recent book, Der rätselhafte Tod des René Descartes (“The Mysterious Death of René Descartes”), the German philosopher Theodor Ebert asserts that Descartes died not through natural causes, but from an arsenic-laced communion wafer given to him by a Catholic priest. He believes that Jacques Viogué, a missionary working in Stockholm, administered the poison because he feared Descartes’s radical theological ideas would derail an expected conversion to Catholicism by the monarch of protestant Sweden.

«Viogué knew of Queen Christina’s Catholic tendencies. It is very likely that he saw in Descartes an obstacle to the Queen’s conversion to the Catholic faith», Ebert told Le Nouvel Observateur newspaper.

As a Roman Catholic in a Protestant nation, he was interred in a graveyard mainly used for anabaptized infants in Adolf Fredriks kyrka in Stockholm. Later, his remains were taken to France and buried in the Abbey of Saint-Germain-des-Prés in Paris. Although the National Convention in 1792 had planned to transfer his remains to the Panthéon, they are, two centuries later, still resting between two other graves — those of the scholarly monks Jean Mabillon and Bernard de Montfaucon — in a chapel of the abbey. His memorial, erected in the 18^th century, remains in the Swedish church.

In 1663, the Pope placed his works on the Index of Prohibited Books.