The unfathomable mystery of the Virginia Tech killings comes down to this: What snapped?
There are innumerable smaller questions, and many will be answered in the hours and days and weeks to come. How were the shootings carried out? Why was there a gap of two hours between the first killings and the others? What were the police doing? What are the lessons for campus security everywhere? And what can we say about the lives of those now dead?
But to understand how someone could connect the grievances of his life to the murder of so many - most of them, presumably, strangers - defies explanation. And it's the question that lies at the heart of this sad and horrifying event. We condemn but perfectly well understand why a drug dealer kills a rival, or a witness; even a bomb in a market in Baghdad is set off with an eye toward a political goal, as abhorrent as it might be.
But death for the sake of death - how does that come about? The empathy that marks us as human seems to run so deep. Is it really so easily discarded?
These, of course, are violent times. The number of shootings is soaring in Philadelphia. Police club demonstrators in Moscow, breaking bones and cracking heads. Yesterday, at least 43 people are reported killed in Iraq; the bodies of 16 others turn up, to be added to the 30 found Sunday. A bomber kills 10 in Afghanistan. In Darfur, 200,000 people are dead - or is it 400,000? No one is sure.
American society is drenched with aggression, and with the sort of aggressive posturing that seeks to humiliate the other. Think of the road rage on Interstate 270 last week, escalating from a thoughtless maneuver to obscene gestures to the deaths of two motorists as their car was forced off the road. And over what?
The massacre at Virginia Tech was over something, maybe something just as stupid and petty. What it was probably won't remain a mystery for long. But it won't be sufficient. It won't be a reason to kill so many people going about their lives, early one morning in the shadow of the Blue Ridge.
The survivors at Virginia Tech will spend their lives recovering from this act of madness; for the families of the victims, it will be much harder. None can ever know what happened to turn one man into an agent of random death, because it happened inside him in a way that's impossible to comprehend. He was once one of us; with frightening sureness, he turned against us.