How my children grow when I'm not looking

I am a full-time parent. I look at my kids all the time, know every part of them: their cuticles, like tiny ragged tissue threads. The soft brown hair in the small of Dora's back, and the taut springiness of her skin; the way it contains her, and the sheen it casts as she bends and moves around the yard. Bea's half-moon teeth, white as a glass of milk, and the glistening pink gaps between them. I rely on these things unconsciously, the way I rely on my front door key fitting its lock.

Yet somehow, when I am not looking, my children change. When did Bea go from baldness to a head of thick, straw-colored curls? At what point exactly did she begin speaking in full sentences?

I am fascinated when I see photos of my children from one year ago. How did the shape of Dora's face change so dramatically without my noticing? When did her cheeks and jawline go from comical roundness, at age 3, to sculpted and mature?

Did it happen on her fourth birthday, or on the day she first agreed to try blueberries in her oatmeal, or during our last trip to the museum?

Lately, I've taken to lingering in my children's room just before midnight. I let my eyes adjust; I add or remove flowered sheets and bedcovers, open or close windows according to my own comfort. I hover around their beds, taking them in with all five senses until I'm certain just the look in my eyes could make even Bea, now 2-1/2, self-conscious.

Such indulgence is rarely afforded a mother of two small children. So I let myself. Weekends away with girlfriends, finishing a long novel in two rainy days at the beach, are sweet but distant memories. I surrender to this far more powerful - if exhausting and occasionally exasperating - phase of my life.

I stand staring at Dora, listening to her deep, rhythmic breaths, each one an abbreviated sigh. I watch her thumb and forefinger move rhythmically over the worn satin ribbon around her stuffed-lamb's neck. Smell her breath, no longer without odor, as I lean in close. A person's breath now, inoffensive but unmistakable. She has bathed, but her cheek is sticky with the dewy sleep-sweat.

I let my lips rest against her face a second or two longer than she'd ever allow if she were awake. At 4, she is already awkward at a gaze that goes on too longingly or lovingly, or a touch so tender it transcends normal skin-on-skin contact.

Bea is still in her crib, and I cannot lean in far enough to kiss her. Instead, I pick up a naked ankle and foot, consider its surprising weight, study its texture and pinkness, and then put it down gently. I run my hand over her ears, eyes, nose, mouth, chin. Marvel at how a face so intense with emotion hours before - ears red with emotion, eyes and mouth harmonizing to form a perfect, joyful shriek, nose and chin dripping with frustrated tears - is now serene in its blankness.

I place a large palm across her chest to feel her tiny heart beating. Then I realize as I slow my own senses down to feel it - tuning in takes a few seconds - that these are among the most privileged moments of my life.

This is when and how my children grow. I am sure of it.