IT ARRIVED recently, this anniversary of the I birth of our second-born. Its coming made me look at this middle child and think: somehow she has survived us and her own stirrings and rebellions. Remarkably, she has even sensed when to admit to us, "You were right," innately understanding that her all-knowing yet doubtful parents needed her reassurance.

The years spin backward as the year of her birth comes into focus -- 1965. The turbulence of the outer world took a back seat to this event. How minuscule she was! Too tiny to be held long in parental arms, her first days were spent, not in the incubator of parental love, but in a mechanical womb filled with life-sustaining oxygen.

We drove to get her at George Washington University Hospital in early September and, even though it was some time after her birth, still the pink lace outfit designed for a newborn engulfed her.

Babyhood ended abruptly for Melissa. A third sister arrived when she was 18 months old. By 11 months, she was climbing unassisted into her high chair, a sure sign of growing independence.

Our picture album tells it all: her smiles at birthday parties, frowns at ballet classes, and grimaces over her oboe. All the while she was dealing with parents who were struggling to make sense of forces both large and small during the Stultifying Seventies.

Melissa has lived most of her life in the same house in Washington. It is a typical city home in an urban neighborhood. She's known poor people who were kind as well as others who were mean. She has known others rich and cruel as well as rich and loving. She has numbered among her friends and acquaintances whites and blacks and Hispanics.

Her observations have given us occasions to teach. "Why can't those men on the corner at least work? Why do they just stand there?" she asks at age 10. And it is off to an ideological give and take about American wealth and poverty, racial and class oppression, opportunity, hard work -- and compassion.

The stories and theories are legion about middle children, and Melissa both embodied and contradicted all of them. She changed subtly -- from the brattiness of puberty to an adolescent who was a teacher, teaching even her mother on occasion. When I seemed unable to penetrate the wall her older sister built around herself at 16, the middle one taught me that there was nothing I could do but have patience.

She even enjoys sitting and talking at length with adults in a way that reminds me of my own childhood in the South.

Not too long ago, she told a family friend that, when she turned 16, she wanted to become a snappy dresser, drive a car, moving into life's fast lane. At the same time, she has begged to let adulthood come slowly and naturally. It seems a not-too-difficult proposition -- she still likes summer camp and riding horses and teaching dance class to the younger ones and eating red licorice -- and dreaming. When she is afraid, she can almost name her fears, a first step toward conquering them. And when she rebels and commits an offense that really riles her father and me, she fights through for an answer as to why she did it -- her answer, not ours.

Though Melissa and I were not together on that recent special day -- she was deep in the mountains of Pennsylvania -- my memories stirred. I said a prayer of thanks, smiling from very deep within