“Remember when you were first old enough to sit in the front seat and your mother was driving and she would swing that hand out and it was so annoying?” my friend Nancy was asking.

Sure, I remember.

“But now,” Nancy continued, “I find myself doing it. Like, ‘Ah! The train is coming!’ Here comes the arm.”

And I’d thought it was just me: Just me with the mom who considered herself a human safety belt. Just me, in turn, driving my kids crazy by yanking them back from the train (even though I already make them stand so far back they can’t even feel the whoosh).

All of which makes me realize two things:

A: Most mothers are paranoid nut jobs constantly freaking out about death.

B: Barbara Boxer got it right.

Right about the Condi thing.

Last week, you’ll recall, Senator Boxer, a Democrat of California, got into a big to-do with Secretary of State Rice at a hearing on the proposed troop surge. If the president sends in more troops, the senator asked the secretary, “Who pays the price? I’m not going to pay a personal price. My kids are too old and my grandchild is too young. You’re not going to pay a particular price, as I understand it, with immediate family.”

Gee, couldn’t she be a little gentler and just stab Ms. Rice through the heart?

Later, Ms. Boxer insisted she’d only been trying to create a bond with the secretary. As in, “Hey, look — we’re twinsies. Neither of us has a child the right age to serve.”

But the remark hit every female nerve. It was, as Rush Limbaugh so graphically put it, a blow “below the ovaries.”

It is almost impossible to think of any situation when it would be a decent thing to point out that a woman is childless. Whenever the Bible mentions a female in this condition (and boy, does it ever), the fertile women are taunting her. The husband is taking another wife or two. The woman herself is generally beseeching God to open her womb.

As a woman who beseeched for many years, I recall there was nothing worse than being reminded — usually by a cabbie — of the life-changing transcendence of parenthood. “I have four children. You? What, none? You are really missing something.”

Thanks.

Now that I’ve got the offspring, there is one thing I really miss from my old life: Sanity. That blissful lack of constant worry, fear, and, in particular, knee-buckling empathy.

When I used to read about, say, a fire that killed six people, “two of them children,” I’d wonder: “What, the other four weren’t as important?”

Now all I can do is turn the page as fast as I can. The idea of children — toy-hugging, nose-picking, crust-shunning children — dying is literally too much to bear. And when I think about their parents.

“It’s like a part of you wasn’t activated yet,” is how my friend Beth puts it. For her part, she no longer can go to sad movies involving children. Ever since having her son, “I’m a puddle,” she says.

It is this electric and unbidden connection to other children, to other parents, and, of course, to one’s own children that’s different about mothers. Not that non-mothers can’t love and care fiercely about the world’s young people. Just that this feels like a change in the DNA.

For all I know, a man’s DNA changes, too, when he becomes a father. Then again, the camping manuals don’t say, “Never disturb a father bear and his cubs!”

Does this protectiveness — maybe over-protectiveness — make a person better equipped to decide a nation’s defense policy? I don’t know. But it does have a way of turning “troops” into “children,” into “someone’s dearest beloved out there eating Army rations in a terrifying place. And to think that just a few years ago he wouldn’t even eat his crusts.”

The instinct is to throw out your arm and pull him back.