"Shoveling warm human hearts and bodies into the furnace" (see below).

It happened during the First World War, then again as the Final Solution. The Holocaust replicated the First World War. First the slaughter of millions of soldiers, then the murder of millions of Jew. Each group of human beings thrown into a furnace. The Holocaust occurred in order to TELL US WHAT THE FIRST WORLD WAR WAS.

We can PRETEND that the killing brought about by nation-states in the First World War was accidental (the "big lie"). But we can't pretend that the killing of Holocaust was accidental.

The Holocaust occurred in order to "awaken us to the nightmare of history." 

Harry Pearson, reported by Winifred Holtby "Pearson told me about all the enormities he had seen at the front: the driving--the callous, perpetual driving by some great force which shoveled warm human hearts and bodies, warm human hopes, by the million into the furnace.”