THE SHADOW CLUB

Popular science on an elusive subject by an Italian research fellow working in Paris.

Casati started ruminating seriously about shadows while watching a lunar eclipse seven years ago. His understanding of the moon had been limited, he realized, until the very moment that the earth’s shadow completely extinguished the nighttime glow. So, Casati thought, shadows obscure, but they also illuminate. How does that happen? He started reading fiction and nonfiction, ancient and modern, about how shadows are perceived, how they are formed, what purposes they actually serve in daily life on planet Earth. Casati's reading took him back to the seventh book of Plato’s Republic, as well as to sources ranging from Galileo to Piaget to the Koran. Despite the lucid translation and abundant illustrations, portions of the text are quite likely to be difficult for readers without extensive knowledge of physics and geometry. It turns out that while shadows are the “great antagonist” of vision, those same shadows are necessary to vision: “The information carried by shadow is a fundamental aid to seeing.” For those who cannot grasp the actual science behind that counterintuitive concept, Casati offers analogies and metaphors galore, including an especially useful one involving the use of a racket while playing tennis. The four-page appendix, “Shadow News, Shadow Facts,” is also helpful.

An earnest, sometimes compelling attempt to explain an everyday phenomenon, perhaps immune to human understanding.