There is no more rock solid generalization of moral certainty, today, than Hitler was evil. It's incontrovertibility is tantalizing. And yet, for the truth of Hitler's evil to be irrefutable, it seems to need to be constantly proven. We need to be constantly reminded of how evil Hitler was. Those who cannot remember the past are condemned to repeat it said George Santayana.
We need to be reminded that there are certain things, we know we know. And we know we know them because they are true, well beyond the selfie photo op, meant to remind people, yet again, as if they needed to be reminded, that Obama is not Bush... My goodness gracious!
Loosing sight of the certainty of what we know we know, even if only so slightly as to be mistakenly interpreted, opened the door to someone who was also watching and interpreting. Putin had reset button ideas of his own. Putin can also take selfies.