Another Virginia Tech shooting means that the nightmare of the deadliest mass shooting in American history is being re-lived by countless people this afternoon.

Few of us forget that on April 16, 2007, Seung-Hui Cho, a senior at Virginia Tech, shot 32 students and faculty before committing suicide.

Now, two more lives have been lost, including that of a police officer. The gunman remains at large.

Tragedies don’t die easy deaths. They tend to go into hiding, at the backs of our minds, laying dormant. They can be reawakened to traumatize us, again. And so it is that today murderous violence brings not only the horror of new losses, but opens old wounds and traumas that had partly, mercifully healed over.

Virginia Tech officials, no doubt, understand this and will ready resources to counsel not only those directly traumatized today, but those indirectly traumatized by demons from the past, now stirring in their memories.

We are—all of us—stories. The pages of our lives are inscribed with those events through which we live, and the thoughts and feelings they provoke inside us. And so today, a gunman, whoever he or she may be, has reminded us how vulnerable we all are to the acts of madmen. That gunman has reminded us that history can repeat itself, in no small measure because dark chapters in our history can elicit new destructiveness from those who have descended into evil. The blood stains on the campus of Virginia Tech were long ago washed clean, yet today they beckoned someone intent on spilling more blood.

We should be reminded that those attracted to darkness and intent on perpetuating it will always be among us—whether they be loners, or leaders of rogue nations. In every case we should be acting on the earliest signs that such individuals are about to spill blood, because we human beings have a terrible habit of waiting too long to believe that the worst could actually unfold under our watch. We too often deny evidence of human destructiveness until even the telltale shadows it casts disappear into darkness.

As days and weeks go by there will be an effort to describe this newest shooter as not human at all and beyond all understanding. Yet, that would short-circuit another opportunity to explain how individuals lose all empathy and all regard for their fellow man and fall into league with the devil. It would short-circuit another opportunity to identify those moments during which the last flames of humanity were still flickering inside this individual—those moments before all hope was lost—when more could have been done. And I promise you: More could have been done.

At some point, we are going to have to accept that cultural and psychological forces are now at work that are leading to more episodes of senseless violence in our population. It isn’t beyond our understanding and it isn’t beyond our control, unless we resolve that it is. God willing, we shall not.

Dr. Keith Ablow is a psychiatrist and member of the Fox News Medical A-Team. Dr. Ablow can be reached at info@keithablow.com.

Dr. Keith Ablow is a psychiatrist and member of the Fox News Medical A-Team.