When I was kid, nine years old in 1965, I read about and saw TV historical programs about World War II, 20 years prior, and thought it was something that had happened in an ancient time, so long ago that people were different, had evolved way past such horror.
Tomorrow we mark 20 years since 9/11. Being an old coot now, I realize that couple of decades was nothing more than a barely perceptible blip in the long stretch of time.
What I know now is those horrors, WWII and 9/11, changed us as a nation, both for good and for evil, and we are who we are today because of them.
WWII brought us together, taught us the value of sacrifice and righteous resistance against the evils of the tyrannical empires we fought. Conversely, it convinced us we were the richest, most powerful empire in the history of the Earth, able to exert our will over any and every other nation on the globe, and had the god-given right to do whatever the hell we wanted no matter how it affected anything or anybody else.
9/11, too, reminded us about sacrifice and righteous resistance against the theocratic hoodlums of the world. But, like WWII, it made us suspicious of other cultures and other religions, willing to sacrifice our liberties for some imaginary sense of safety and security, and filled to a certain extent in all of us with a vestigial sense of hatred and fear.
The thing that never changes is evil begets evil.