Not long ago I took a shopping bag full of clothing to a children's consignment store called Milk Money. In it were pint-sized sweaters and dresses, a plush red snowsuit that all four of my children wore as infants, and slippers in the shape of cowboy boots that I could no longer squeeze over my toddler's toes. I also brought along a breast pump that I had recently retired, when said toddler turned one.

The clothing stayed at the store, awaiting new life in someone else's closet. The breast pump, however, came back home with me. It wasn't that the owner of the store turned down the pump. It wasn't that somewhere deep down I thought I might need the pump again. Despite my not-so-secret desire for "just one more baby" (this is the part where my friends will roll their eyes; my oldest is going to college next year!), the odds are against that happening.

Now you may be wondering why in the name of Hera, the Greek goddess of motherhood, I'd cling to a contraption that's in some ways a torture device for the mammaries. After all, pumping is nothing like nursing an infant. No rosebud lips latched on to your nipple. No starfish hands kneading your breast. No satisfied, satisfying gulping to tell you that what you're doing, right at this minute, is one of the most important things you'll ever do in your life. If you've ever used a pump yourself, or seen one in use, you know what I'm talking about. Pumping is to breastfeeding as a vibrator is to making love: a mechanical substitute that gets the job done all right, but without the love part.

And yet, I seem to be attached to my breast pump in a weirdly emotional way. In the weeks since my visit to the ironically named Milk Money, the pump has sat in a corner of my bedroom, prompting me on occasion to contemplate its strange hold on me. Somehow, between checking homework, signing field-trip slips, wiping noses, wiping bottoms and wiping tears (not to mention juggling my own work deadlines), I think I've figured it out. My breast pump is a symbol that even as a working mom, I'm a good mom.

It's like this: I worked throughout all of my pregnancies and went back full time at the end of each maternity leave. When my first baby, Will, was born, I had every intention of keeping up a supply of pumped milk for when I was at the office. Here's how my first day back on the job turned out:

At around three in the afternoon, the phone rings. It's Will's nanny, Thelma. "You need to come home right away. Your baby's very hungry."

"Oh, no, there's plenty of milk in the freezer," I say.

"He drank it all."

It's just four words, but they're packed with meaning. What Thelma's telling me is that every drop of milk coaxed from my breasts over the past few weeks, decanted carefully into tiny plastic bags and festooned with red twist ties, is gone.

"I'll take the next train," I say, calculating how long it'll take me to get home.

"He can't wait," says Thelma. "I'll have to buy formula."

I wince. Will's screaming right into the phone. I guess Thelma's holding him near the receiver now (to comfort him? to make a point?). "There's cash in my top dresser drawer," I tell her. I hang up and burst into tears.