On a recent trip to Paris, researching my book Footnotes, I regularly stepped out for a run. My route invariably took me past the Panthéon, the large, neoclassical domed mausoleum some eighty metres in height. Despite many visits over the years, my association with that building was in fact first forged when, at the age of twenty, I read about how Léon Foucault in 1851 put its dome to experimental use by swinging a pendulum from it to demonstrate the rotation of the earth. The explanation of this experiment appeared in the opening pages of a novel that I was then under the spell of: Foucault’s Pendulum by Umberto Eco.

Unlike the tight geographical containment that characterises Eco’s first book, The Name of the Rose, Foucault’s Pendulum is a great sprawling adventure that leaps as easily across continents as it does through periods of history. Its central characters are so obsessed with conspiracy theories that they invent one