I'm having trouble, as usual, coming to grips with the human condition.

I've been hanging around a children's hospital -- practically living there, actually -- where my teenage daughter is recovering from major surgery. The doctors are pleased. It has been a successful operation. Everything has gone well. So far, so good.

All this should be enough to calm a mother down. But it's not -- not completely.

I'm still coming off many weeks of a ferocious nervousness that I hadn't known I had in me. There has been the unsleeping, the preoccupation, the impatience and the disorganization. There's been the chewing of pens, fingernails and fists, the frantic searches for things that wind up being under my nose.

Perhaps most unnerving of all, images of my daughter's life keep passing through my mind (perfect baby feet; favorite books and toys; interests and passions).

I talk to other mothers who have been in this situation. Their stories of anxiety and the forms it takes are similar.

They tell me other things, too: Don't expect this fright to go away right away, even if the child keeps improving. Don't expect fathers to express themselves in the same way. Eventually, we come out on the other side, but we're changed. Take care of yourself. Hang in there. Keep us posted.

What about the ones who continue to be in this situation year after year, or the ones whose children never leave? I'm afraid to ask.

In the hospital, I think I can identify some of those parents and other family members who are in the thick of things. They look hunted or distraught, as if they're just hoping they can somehow survive. I see weeping into public phones.

Those whose children are in surgery or recovery are an especially quiet lot, waiting for any kind of news. There is the grainy look of fatigue everywhere. We are like some of the fish in the fish tanks here, peculiar brown things that can hang from vertical surfaces by their jaws.

Of course, most of the time my attention is not on other people in the hospital, but on my daughter. I sit in a chair by her bed, keeping vigil. Friends and flowers and phone calls arrive with comforting regularity. But I see her confused, frightened and in pain -- sometimes terrific pain. ("She's achin'. She's really achin'," her little brother tells a family friend.)

She's confined in a bed and on her back. She has no privacy or independence. She's hooked up to machines, and needles keep showing up.

Medical people come and go. They are wonderful to her, but they are strangers, and she understands perfectly that they call all the shots.

And I can see her incision under its strips of special tape. It reminds me of a row of buttons on a beautiful new dress -- everything sewn skillfully and painstakingly, even lovingly, by hand. This is what has happened to that perfect little baby!

All this, and my daughter is one of the lucky majority of kids who find themselves in a place like this. Give them a little medical attention, a little time, and they're OK.

But there is no escaping that some children's main job here is to just keep battling. These are kids who can't be made safe, despite the fiercest love and most valiant efforts of their parents and doctors. Just under the ordinariness of our everyday activity is the terrible vulnerability of the human body -- and of our children.

Stories are all around me. There's the boy who looks perfectly content, but who roars in a crazy way every minute or two. The baby girl, strange lumps on her bald head but earrings in her tiny ears that seem to say, "The heck with you, Cancer. I will be a fetching young woman someday."

The story that really gets to me is the teenage boy -- another bald child -- walking into the hospital as calmly and as purposefully as if he were walking into school. (Oh, we're just having a normal, everyday day, dum-de-dum, we know where we're going.) The grownup dropping him off at the curb (a grandfather?) is fuzzy around the edges, gray and depleted. He gives me a wan smile.

This is where the voices coalescing in the back of my head break through. "It's not fair. Why should children have to suffer like this? How could something like this happen?"

Of course, fair and should have absolutely nothing to do with it. Children have always suffered, and died, from natural causes, just as adults have. It's nature's way.

But how can we parents come to grips with this? How do we live with our anxiety and our grieving, the cost of being so crazy-in-love, so deeply and so terribly attached?

This is something I never really anticipated when I joined the ranks of mothers. I never really anticipated the joy, either. One thing's for sure: You're not the same person coming out as you were going in.