For three generations, the Lévis had never thought of themselves as anything but French. Their tall house had a fish pond and, until they had recently been cut down, the oldest lime trees in Paris, and was hidden away on a tiny street on the Left Bank. The third Monsieur Lévi, André, was a mathematician who had been a child prodigy in the field of rational numbers and algebraic geometry and for two decades had been an eminent professor at the École Polytechnique, until Jews were asked to leave. He thought the next few years under the Germans must be navigated as a maze would be, and at this he was expert. There was a small maze of hedges in the garden, and it was here the professor first taught his son Julien about spatial analysis. He had often brought him to the garden at the Château de Villandry, where a Renaissance maze signified the progression of life. He would blindfold Julien so that the boy could feel the geography and learn to visualize spatial relationships. In time Julien became astoundingly good at running the maze without stumbling over the hedges, excellent practice for a mathematician who must be willing to believe there is a logic to all things.

In his everyday life, André Lévi continued to think of number theory, the study of whole numbers that traced back to the Babylonians. His special professional interest was the speed with which the universe was expanding, in part by refining the use of Cepheid stars as yardsticks. For him the world was divided, and because of this he often didn’t see human beings, not even those he knew intimately, whether they were his wife or his two sons, Julien and Victor, or the young housemaid, Marianne. Professor Lévi had managed to keep the house by paying off a local magistrate. Each week more of their belongings were sold in order to do so, first the paintings off the walls, then silverware from the table, then the cameos in Madame Claire’s mirrored jewelry box.