And sometimes a wretched pathetic excuse for a human being like your current "President" can set the clock back a hundred years in that process, but still and all, over the centuries, the human race does progress to an increasingly more humane and less savage state. Seen anyone fed to the lions for public amusement lately?
After 9-11, all you had to do was turn on any radio talkshow to hear all the grotesque things people wanted to do to punish any Ay-rabs, camel jockeys or towel heads they might run across. There are always a few people who can rise to ghastly barbarism in a crisis, and every once in a while, as in Bosnia, they do.
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Marine basic training still repeats a routine where the entire company shouts Kill!! Kill! kill! rather a large number of times.
So some are born barbarous, others become barbarous, and yet others must have it thrust upon them.