If we never forget, we will never stop learning.

	Damaged beams from the World Trade Center towers are displayed at the 2002 California State Fair. Fairgoers wrote inscriptions and placed remembrances on them before officials put a barrier around the display, which will become part of a permanent memorial. Sacramento Bee/Bryan Patrick

"Those who cannot remember the past," said the American philosopher George Santayana, "are condemned to repeat it."

But learning from the past is no easy thing.

And putting its lessons into practice is even more difficult. The images of Sept. 11, 2001, are still clear to most of us: the unspeakable evil of the terrorist acts; the numbing horror; the wrenching tragedies; the selfless heroism; the inspiring kindnesses of strangers.

But the lessons of that day are less clear, and it may take many anniversaries before they all come into focus. Maybe the best we can do is keep the images of those events in our minds and hearts.