Today is Holocaust Memorial Day, a day of commemoration dedicated to the remembrance of those who suffered in The Holocaust under Nazi persecution, and in subsequent genocides in Cambodia, Rwanda, Bosnia, Darfur and elsewhere. In this, an extract from Why Did the Heavens Not Darken?: The "Final Solution" in History, Arno J. Mayer analyses the structure of rememberence and the task of the historian in relation to the Nazi Judeocide.