Lessons Can Be Lessons and Remain Unlearned

People rise to debate lessons learned
Or learnable from the worst horrors
People commit—specific lessons

From specific horrors, general
Lessons from horror generally,
And occasional declarations

That there is nothing to be learned. Fine.
At a minimum, every horror
Committed by humans, of itself,

Ought to teach humans at least two things:
That it is possible for humans,
Having done it, to do such a thing,

And that, having done it once, it is
Possible we could do it again.