How did Spain live with the slaughter of their rampage across South America? How did the torturers of the Spanish Inquistion live with their cruelty? How did the Turks live with what they did to the Armenians? How did the folks leading the Tulsa Massacre live with what they'd done? How did the Nazis? How did the Ba'ath party in Iraq and Syria? How did Russia in Syria? How did America with babies in cages?

As you write, "This is insane – just pure insanity." It's mankind's native inhumanity and our greatest talent – the ability to justify anything in the moment, no matter the horror we cause.