Learn what? That good walls make good neighbors? Especially when they're trying to invade you?

Tell me what changed? We're back at it with Russia. Seems we're ready to rebuild that wall that divides us. There's serious talk of WWIII.

So, what good did tearing that wall down do?

People who are fundamentally different shouldn't be FORCED together...it causes conflict. That's why ALL our "integration" policies fail. We're really not meant to be living together, the differences are too vast, insurmountable.