Foucault's Pendulum is narrated in the first person, albeit with occasional omniscience (thanks to Abulafia's files), by Casaubon. He is like the old sailor in Coleridge's "The Rime of the Ancient Mariner" (1798) at once a guide and a survivor. The novel begins at 4 p.m. on June 23, the eve of the summer solstice, as Casaubon hides in a periscope at the Conservatoire des Arts et Metiers in Paris. The image of Casaubon observing through the narrow field of vision afforded by a periscope is emblematic of the perspective that he has (and the reader has) throughout the novel: An individual person's vision is not all-encompassing, but necessarily restricted. Despite the fact that the hunger for vision and for faith is sometimes insatiable, human knowledge remains innately limited. Encyclopedic as Casaubon's (or any-one's) knowledge may seem, there are still gaps, shortcomings, and blind spots. One precondition for obtaining knowledge...