In the two weeks since the tragic massacre at Virginia Tech, we have learned a great deal. We learned that Seung-Hui Cho had been troubled his whole life and that, despite several attempts, the mental-health system was not able to provide the care he needed.  We learned that he was bullied and that no one helped. We learned that in Virginia, as in many other states, guns are readily accessible.

But we did not learn what we really want to know:

How can we find security in a world that feels increasingly insecure?

Security is a fundamental human drive, more primitive and primary than even love. The shootings violated our sense of security, so some things will change.  Most will not.

We are increasingly security-conscious as a nation and as individuals.  Gated communities have cropped up in pursuit of security. People are buying handguns for security. We push ourselves and our children relentlessly - also about security.

Yet most people still don't feel secure because the kind of security we really want doesn't come from alarm systems. What we want is the feeling of security we experience at a gathering with people we deeply care about and who care about us.  Or the feeling we experience when we are so devoted to someone or something that we temporarily forget our own needs.

More metal detectors and better-trained campus police are coming, along with ever-louder debate about gun laws. And although it has become evident that the mental-health system, both public and private, is woefully inadequate, that probably won't change much. Why?

Dramatic change requires more than money and legislation. It requires changing our thinking about how we care for people with psychological problems.  Ultimately, it challenges us to change our thinking about how we care for one another.

I attended a lecture in Philadelphia several years ago by Deborah Prothrow Stith, associate dean at Harvard medical school and an expert on youth violence prevention. She was the mother of young children, and pointed out what may seem obvious: Most of her time, energy and resources went to them. It's just a fact of having children.  She went on to say that if she did not invest her resources in her children when they were young, they would require even more as they got older.

It seems that her prediction is coming true on a national scale. Leisure time at home with the kids is decreasing. So-called entitlement programs that take care of young children and families are shrinking. At the other end, violent killings and prison populations are growing.

As individuals, we must invest more time and energy and resources in all of our children. We know there are many small children out there who feel alone, isolated and uncared for.  If everyone could find an hour or two each week to invest in children, it may just change the world.

We don't know what would have happened with Seung-Hui Cho if more adults had shown a genuine interest and perhaps protected him from bullies as a child.  But we do know there are many more children out there who need that kind of help.

Two hours a week at a local elementary school or boys and girls club can change the world.  Not only that, but a personal commitment to helping our nation's children will expand our own networks of people we care about. This alone will enhance that feeling of security.

And for the children?

Every person I've met who overcame great adversity as a child has told me that at some critical point, there was someone who believed in him or her. I wonder if Seung-Hui Cho had one.