The earthly remains of René Descartes have been disinterred several times since his death in 1650, and with each disturbance, some of his bones vanished into the hands of venerators. The irony of the material legacy of the philosopher of reason being regarded similarly to the relics of saints is not lost on Shorto, who pairs a detective narrative with his thoughts about what the story reveals about skepticism versus belief as features of modernity. As Shorto relates, uncertainty about the authenticity of the contents of Descartes’ coffin accompanied its travels from Stockholm to Paris in 1666, culminating––when a skull purportedly that of Descartes surfaced in 1821––in an inquest conducted by the French Academy of Sciences. After describing subsequent attempts to fix the provenance of Descartes’ remains, Shorto tenders his speculation that they were lost in the turmoil of the French Revolution. Giving rein to his curiosity about the postmortem Descartes, Shorto will pull in readers who enjoy a good history mystery seasoned with philosophical thoughts.