Nineteen years ago, Sept. 11, 2001, the world changed.

It is easy, sometimes, to forget that, with all the distractions and false idols before us all each day.

But for many of us, alive and aware that day, and by the end of that day grieving mightily for friends lost and our beloved country attacked, it is a day we can never forget.

It is etched in national memory.

Sept. 11 can be compared only to the day President John F. Kennedy was shot and killed or to Pearl Harbor Day — “a day that will live in infamy,” as Franklin D. Roosevelt said.

It is worth remembering what we learned:

We learned how vulnerable our nation can be.

We learned the depths of heroism in our first responders, whom we’d perhaps thought about too little and perhaps once more think about too little.

We learned anew how much we need the armed forces and the men and women of the armed forces. The world is a dangerous place.

We learned that there is evil in this world — vicious hate which has no limit and is often fed by absurd ideology and perverted religion.

We learned how much we need a smart, crafty and apolitical intelligence community. (We quickly let down our guard on that one.)

We learned that we don’t need an excuse to fly the flag and that doing so makes most of us feel good.

We learned, for a moment, that when the president is respected by the public, even those who did not vote for him, and he or she tries to bring us together, it is good for the country.

And we learned how much stronger we are when we find moments and reasons for national unity. It’s one reason we have national holidays — not just to get days off but to celebrate our country.

We learned to be wary, and careful and not take so much or so many for granted. But, most of all, we relearned this old lesson of looking for the ties that bind and celebrating those ties.

Another word for that is patriotism — love of country.

As we remember 9/11, let us exercise and apply that love.

— Tribune News Service