Perhaps it was the way the sunlight hit her face. It was bright and unforgiving. Or perhaps it was just a mother looking at her own daughter with new eyes.

But on a recent ordinary summer afternoon, as I sat outdoors talking with Amy, our middle daughter, I noticed an unmistakable crinkling of lines around her brown eyes. Amy – who used to watch me camouflaging my own squiggly lines with makeup and would ask, “Why are you putting on that junk, mom?” – is clearly showing the signs of being 40-something. The irrefutable fact of that new decade in Amy’s life still stuns me.

And could that truly be gray running through her auburn hair? This was, after all, the same decade when her father’s hair made the journey from auburn to gray to silver. And Amy is her father’s genetic double. For a crazy moment, I fought an overpowering urge to stop our conversation and say, “Hold everything! There’s been a mistake here.” I wanted to reach out, take her hand, and lead her back to another time when she was shielded and protected from the vicissitudes of adulthood – including wrinkles.

But Amy, like her sisters, is no longer that child of tender years for whom I can order and detoxify the world, at least to the extent that any parent can for any child. The historical data I’ve stored up in my bulging memory bank of Amy is just that: history. And even though we continued talking in the dwindling light of late afternoon, while Amy’s own children darted in and out of our immediate field of vision, I couldn’t concentrate anymore.

I was searching for clues as to how these years between sweet dependency and total womanhood/total independence had slipped away while my back was turned. I was once again playing out that oldest quiz question of mothering: “How did it all go by so fast?”

And in that sweepstakes, there are no grand prizes except bafflement. For the rest of that day, I watched my daughter navigate her world, one currently defined by all the responsibility of a working wife/mother with two little girls.  I watched a woman, not a girl, move from the exhilaration of motherhood to the exhaustion and exasperation of it, sometimes in a matter of seconds. Amy, I had to remind myself, was doing all this in her 40s. I’d done it almost two decades earlier. Did I, too, have that edge back then of alternating anxiety and joy, pleasure and pure frustration? Was my life then as defined – and confined – as hers?

Of course it was. And I had to concede that while we shared this common experience, Amy was doing the job with considerably more wisdom and knowledge than I had brought to the calling as a younger, less confident, mother. But the lingering impression of that long afternoon with my daughter, as I watched her talk, smile and gesture, was reduced to a single, startling notion: this person, so known and loved, is a woman in her 40s. And showing it.

Despite the thousands of times I had looked into her face, I had never seen it as clearly before. No vestiges of that little girl with the rounded cheeks she hated, and a mop of curls she coaxed out of existence with – dare I say it – an iron! The person facing me was not trying to halt time with the ministrations of doctors or magazine-touted products. She was what she was:  a wonderful, accomplished woman in her 40s. And I’m not sure why that notion is so startling. I just know that it is.