Foucault's Pendulum

Lore & Background

The book opens with a man named Casaubon hiding in the Musée des Arts et Métiers after closing. He believes that a secret society has kidnapped his friend Jacopo Belbo and is now after him, and that they will soon convene in the museum. As he waits, Casaubon reflects on his life, but it is implied that he is an unreliable narrator whose mind has been warped by conspiracy theories. In the 1970s in Milan, Casaubon, who as a student had participated in the 1968 Italian uprisings, is studying the Knights Templar for his thesis when he meets Belbo and his colleague Diotallevi. Belbo works as an editor in a publishing house and invites Casaubon to review a manuscript about the Templars. The manuscript, by Colonel Ardenti, claims he discovered a secret plan of the Templars to take over the world, basing it on a mysterious note written in an ancient code. Ardenti mysteriously vanishes after meeting with Belbo and Casaubon. Casaubon then moves to Brazil to pursue a relationship with a woman named Amparo and meets Agliè, an elderly man who implies he is the mystical Comte de Saint-Germain. Casaubon's relationship with Amparo falls apart after attending an Umbanda rite due to her loss of personal control, and he returns to Milan, where he is hired by Belbo's employer, Mr. Garamond, as a researcher. Casaubon learns that Garamond also owns Manutius, a vanity publisher. Garamond has the idea to begin two lines of occult books. Agliè, now also in Milan, becomes a consultant to Garamond. Belbo grows jealous of Agliè's ability to charm Belbo's former mistress Lorenza. Casaubon enters into a relationship with a woman named Lia, who nicknames him 'Pow'.

Reader's Guide

Belbo, Diotallevi, and Casaubon become submerged in occult manuscripts that draw flimsy connections between historical events, and soon have the idea to develop their own as a game. Using Belbo's personal computer 'Abulafia' and Ardenti's manuscript as a foundation, the three create what they call 'The Plan' using a program that rearranges pre-typed sentences at random to suggest ideas. The Plan becomes an intricate web of conspiracy theories about the Templars and their goal to reshape the world using 'telluric currents', whose focal point can be determined using the Foucault pendulum and a unique map. They invent a fictional secret society, the Tres (Templi Resurgentes Equites Synarchici). As time passes, the three become increasingly obsessed with The Plan. Casaubon talks to Lia, who now has a child with him, and shows her the note the entire Plan is based upon. She analyzes it for a day and a night and reconstructs it — the note was encoded using a modern cipher, not an ancient one, and is actually a laundry list for a merchant. Diotallevi is diagnosed with cancer and attributes it to divine retribution. Belbo, overcome by jealousy over Lorenza, discusses The Plan with Agliè and claims to be in possession of a Templar map revealing the location of a 'valve' that controls the telluric currents. Agliè demands to see it and is refused. Agliè, Garamond, Ardenti, and many manuscript authors convince themselves they are the Tres, and Agliè forces Belbo to accompany him to Paris. Casaubon visits Belbo's apartment and reads his personal files, then goes to Paris and Foucault's Pendulum. In the present, a group led by Agliè gathers around the pendulum for an arcane ritual. Belbo is questioned but refuses to reveal what he knows, inciting a riot during which he is hanged from the cable of Foucault's Pendulum. Casaubon escapes and flees to the countryside villa where Belbo grew up, soon learning that Diotallevi succumbed to his cancer at midnight on St. John's Eve, coincidentally the same time Belbo died. Casaubon meditates on events and finds an old manuscript by Belbo that relates a mystical experience he had when he was twelve, in which he perceived ultimate meaning beyond signs and semiotics.

Did You Know?

• The book is divided into segments represented by the ten Sefiroth.
• Critic and novelist Anthony Burgess suggested the book needed an index due to its dense esoteric references.
• The pendulum of the title refers to an actual pendulum designed by French physicist Léon Foucault to demonstrate Earth's rotation.
• Eco specifically rejected any intentional reference to philosopher Michel Foucault, which is regarded as another subtle literary joke.
• The three main characters create 'The Plan' using a computer named 'Abulafia' that rearranges pre-typed sentences at random.