If you're like me, you may be trying to avoid thinking about today's anniversary as much as possible. But you may find this story by Dan Barry from the New York Times as helpful as I did. You still won't be able to make sense of what happened, because there's no sense to be made of it. You might be persuaded that it "is not about geopolitics, or security, or even terrorism." It's just about the "unpredictable, uncontrollable and arbitrary" nature of death:

Perhaps the first lesson learned, or relearned, about death is the most basic. "It never goes away," said Dr. [Sherwin B.] Nuland, the author of "How We Die: Reflections on Life's Final Chapter" (Alfred A. Knopf, 1994).

"Most people who haven't had a death of someone very close to them don't realize that it never goes away," he said. "They talk about nonsensical things like closure and healing, but what people are coming to realize is that when someone close to you dies, one of the stars you steer by falls from the firmament. If 9/11 has taught us anything, it is about the continuity of loss, and how things are always different after death."