The 400th anniversary of Descartes' birth near Tours has seen the traditional commemorative publications. But one biographer, retired medical professor Emile Aron, found that he spent much of his two years working on his Descartes et la Medecine tracking the peregrinations of Descartes' head.
The skull of the thinker, who proclaimed the separation of soul and body, has been sitting on a shelf in the Musee de l'Homme in Paris for decades - between shrunken heads of Jivaro indians and the skull of a famous 17th-century highwayman.
Sifting through the museum archives, Aron pieced together the story of the head's travels, which, if he has his way, may not yet be over. "I am now campaigning to have the skull transferred to the Descartes Museum in his birthplace," said Aron, who is president of the Touraine Academie des Sciences, Arts et Belles-Lettres.
"The last private owner of the skull was Berzelius, a Swedish chemist who attended the session of the Academie des Sciences at which it was announced that the skull was found to be missing when Descartes' coffin was opened in 1819," said Aron.
"He was shocked at this and at the blame laid on his country, so when he read a 1821 gazette report of the sale of the skull at a Stockholm auction, he tracked down the buyer, bought the skull for FFr37.50 and gave it to the French academy to make amends."
Descartes died in Sweden, probably of pneumonia, in 1650 "after catching cold while being kept up talking philosophy by Queen Christine until 5am," notes Aron disapprovingly. He was buried in a Swedish cemetery for non-Protestants for 16 years, until the first disturbance and depletion of his mortal remains, which were to be returned to France.
The French ambassador who supervised the exhumation helped himself to the first segment of the index finger of Descartes' right hand, as it had been "the instrument of immortal writing".
Whether or not this act inspired one of the Swedish guards attending the exhumation is unknown. He went one step further and stole the entire head, engraving into the bone "Descartes' skull, taken and carefully kept by Israel Planstrom when the body was sent to France and hidden since that time".
On Planstrom's death, the skull was found among his possessions and sold. A succession of owners engraved their names on the bone over the following 150 years.
While much indignity was being inflicted on Descartes' head, his body was faring little better. Its journey back to France in 1666/67 took eight months and although thousands turned out for its laying to rest, Louis XIV forbade any funeral oration. The French Revolution heralded more exhumation and reburial. In 1793, the Convention decreed that Descartes merited the honours of the Pantheon, as "one of the prodigious men who have pushed back the boundaries of public Reason".
But the much-disturbed remains only got as far as transferral to a waiting place in the Jardin des Monuments while a national consecration ceremony could be prepared. But history moved on and brought in the Directoire, for whom Descartes, "the principal cause of the misfortune wrought on the human race, could be left to live and die in his works".
Aron believes Descartes would have agreed that his works, not his mortal remains, were what mattered. The rest of the skeleton never made it to the Pantheon and stays where it was put in 1819, in the church of Saint Germain-des-Pres.
Aron is no newcomer to commemorative biographies. He has previously "spent two years with Rabelais" and found producing Le Docteur Francois Rabelais "much more fun".
"Descartes was a flipping bore, quite unlike Rabelais. He realised God does not exist but could not say so. That hampered his style terribly," insists Aron, "But he is a wonderful example of a thinking man."