Now if it had been Michel Foucault’s pendulum…but the Foucault in this case is Jean Bernard Léon (1819–68), and it is beside his pendulum, a copper sphere on a long thin wire suspended and swinging from the vault of the Conservatoire des Arts et Métiers in Paris, that the narrator Casaubon waits patiently through six hundred pages of post–modernist prose for the climax of Eco’s second novel. So any speculation about the other Foucault’s pendulum would seem irrelevant, even irreverent, except that, having been conjured up accidentally, the shade of the great historian of sexuality hovers inexorcisably over the whole work.

Casaubon’s colleagues at the Garamond Press, ‘a small but serious publisher’ in Milan, are called Belbo and Diotallevi: one automatically looks about for a character beginning with ‘A’. There are three: the first is Abulafia, Belbo’s faithful computer, repository of his confessions and musings, instrument of his anagrammatical calculations whereby