Even to speak of it in a serious way is to feel a bit like a rube, a yokel from some backwoods backwater where nobody ever heard of clinical depression, sociopathy or any of the other terminology we use to explain the cruelties human beings sometimes perpetrate. To ascribe such behaviors to something so vague and indefinable is faintly embarrassing.

But it also feels unavoidable, given the awful anniversary we observe this week. Ten years ago Monday, two boys, Dylan Klebold and Eric Harris, walked into Columbine High in Littleton, Colo., and unleashed hell, killing 13 people, wounding 23 and then committing suicide. In the process, they also unleashed a firestorm of speculation from media-appointed experts, jostling to answer what was suddenly the most important question in the world: "Why, Lord, why?" They told us video games did it. They said years of bullying did it. They said being ostracized did it. They said violent movies did it. They said bad parenting did it.

I said evil did it.

That observation, made in this space, was not especially popular. Small wonder. What do you say after you say evil did it? The very idea stops the discussion, forecloses the hopeful notion that there is something we can do, some measure we can take, to keep this obscenity from happening again. If you say bullying did it, you can seek ways to curtail bullying. If you say video games did it, you can pass laws to curtail video games.

But how can you curtail evil? What law can do that? And yet here we are, 10 years out, and I find myself reading reports on the new scholarship that has sprung up around the Littleton massacre, including a book called "Columbine" by Dave Cullen. And the consensus seems to be that everything we thought we knew about why those boys did what they did is wrong.

Turns out they were not bullied. Nor were they outcasts. Nor were they unduly influenced by violent movies. Nor were their parents bad.

Turns out they were simply two profoundly damaged boys.

Which brings us back to evil. It is, I grant you, a fraught and loaded word. It flies in the face of our innate belief in the perfectibility of human beings, suggesting as it does something that is beyond redemption, beyond correction, beyond our power to fix. Better to think in terms of psychological illness because illness, at least, implies an ability to be cured.

I am not saying psychological maladies do not exist or that they cannot help us understand why we do the things we do. What I am saying is that there are some behaviors so monstrous they dwarf our attempts to comprehend them with psychological verities.

Did Adolf Hitler murder 6 million Jews because he had a strained relationship with his father? Would it matter if he did? Yes, Harris and Klebold killed nowhere near as many people as the Fuhrer, but it was not for lack of ambition. While we are conditioned to think of evil as something that comes wearing a Snidely Whiplash mustache or speaking in a Darth Vader voice, it is more often a banal thing hiding in plain sight just like this, hiding in the incremental moral compromises, failed humanity and grandiose self-image of ordinary men.

Until their fury breaks upon us abruptly as a clap of thunder in a summer storm.

Thus it was with Harris and Klebold. Thus it was with Seung-Hiu Cho after them and Charles Starkweather before. Thus it has been. And will be. Being human requires living with the knowledge that sometimes human beings shatter. And yet still living. So I will not begrudge you if you seek the rhyme or reason in what those boys did, but as for me, I will give them not an hour of my one and only life trying to comprehend their incomprehensible deed.

They've taken more than enough already.