A noted French thinker's poignant reflections, in words and photographs, on his visit to Auschwitz-Birkenau. On a visit to Auschwitz-Birkenau, Georges Didi-Huberman tears three pieces of bark from birch trees on the edge of the site. Looking at these pieces after his return home, he sees them as letters, a flood, a path, time, memory, flesh. The bark serves as a springboard to Didi-Huberman's m…