Foucault's pendulum

Foucault's Pendulum (original title: Il pendolo di Foucault [il ˈpɛndolo di fuˈko]) is a novel by Italian writer and philosopher Umberto Eco. It was first published in 1988, and an English translation by William Weaver appeared a year later.Foucault's Pendulum is divided into ten segments represented by the ten Sefiroth. The satirical novel is full of esoteric references to Kabbalah, alchemy, and conspiracy theory—so many that critic and novelist Anthony Burgess suggested that it needed an index. The pendulum of the title refers to an actual pendulum designed by French physicist Léon Foucault to demonstrate Earth's rotation, which has symbolic significance within the novel. Some believe that it refers to Michel Foucault, noting Eco's friendship with the French philosopher, but the author "specifically rejects any intentional reference to Michel Foucault"—this is regarded as one of his subtle literary jokes.