Editor’s Note: These 5 real characters (and suspects!) appear in Andrew Pessin’s historical murder mystery The Irrationalist: The Tragic Murder of René Descartes. Click here to order your copy.

1. Sweden’s Queen Christina (1626-89)

Queen Christina

Her Majesty invited Descartes to Sweden to become her “Court Philosopher,” and shortly thereafter he was dead. Considering that she was the most powerful monarch in Europe, could that possibly have been just a coincidence?

2. Gisbertus Voetius (1589-1676)

Gisbertus Voetius

Gisbertus Voetius (1589-1676): Dutch preacher, Professor of Theology and Rector at the University of Utrecht, sharp-tongued despiser of all things Catholic and especially of all things Descartes. His permanent scowl obscured what surely was his great joy at Descartes’s death—especially since Descartes had earlier destroyed his career.

3. Gilles Personne de Roberval (1602-1675)

Gilles Personne de Roberval

Large-headed but small-minded French mathematician, whose brilliance would surely have ranked him as the world’s leading mathematician—had not Descartes publicly humiliated him and then possibly stolen his work.

4. Ebba Sparre (1629-1662)

Ebba Sparre

Beautiful, young, intimate “friend” of Queen Christina, with proven ability to indulge in insidious court intrigues. Could she have been jealous of all the attention the Queen was directing to her new imported plaything, the famous French philosopher?

5. Boy-King Louis XIV (1638-1715)

Boy-King Louis XIV

Eleven-year-old boy-King Louis XIV (1638-1715) had many reasons of his own to be jealous of Queen Christina: she was older than he, more powerful than he, and, in fact, more manly than he. And though he wasn’t there in Stockholm, his agent was: Hector-Pierre Chanut (1601-1662), dapper, rotund, French Ambassador to Stockholm, who had reached his exalted position by learning how to lie continuously and to maintain inconsistent sets of false beliefs in at least a half-dozen interacting people at once. If His Majesty was in a tantrum about Queen Christina stealing his philosopher, who was he not to do something about it?