Timothy Snyder in the New York Review of Books:
Though Europe thrives, its writers and politicians are preoccupied with death. The mass killings of European civilians during the 1930s and 1940s are the reference of today's confused discussions of memory, and the touchstone of whatever common ethics Europeans may share. The bureaucracies of Nazi Germany and the Soviet Union turned individual lives into mass death, particular humans into quotas of those to be killed. The Soviets hid their mass shootings in dark woods and falsified the records of regions in which they had starved people to death; the Germans had slave laborers dig up the bodies of their Jewish victims and burn them on giant grates. Historians must, as best we can, cast light into these shadows and account for these people. This we have not done. Auschwitz, generally taken to be an adequate or even a final symbol of the evil of mass killing, is in fact only the beginning of knowledge, a hint of the true reckoning with the past still to come.
More here.