I wasn't looking for this...

There is an answer to the doctor's question. All the Dachaus must remain standing. The Dachaus, the Belsens, the Buchenwalds, the Auschwitzes - all of them. They must remain standing because they are a monument to a moment in time when some men decided to turn the Earth into a graveyard. Into it they shoveled all of their reason, their logic, their knowledge, but worst of all, their conscience. And the moment we forget this, the moment we cease to be haunted by its remembrance, then we become the gravediggers. Something to dwell on and to remember, not only in the Twilight Zone but wherever men walk God's Earth.

The ending narration to Deaths-Head Revisited.