In his office in Paris’s National Assembly, Cédric Villani opens a parcel: it contains a metallic spider. “Lovely,” he says, putting it on a shelf, where a collection of spider-shaped objects sits ...

Cédric Villani’s arrival, one afternoon last May, at a small café off the Champs-Élysées drew glances from a good fraction of the late-lunch crowd. His shoulder-length hair was parted almost ...