All the world’s a beach, and the men and women merely sunbathers, as Shakespeare put it, in that famous speech about remembering to use sunscreen with a high enough SPF, and to reapply regularly after swimming.

The currents of family life hit me hard on the beach every summer. Watching people with their babies, their toddlers, their school age children, their adolescents. Watching the groups of adolescents on their own, without their parents. It’s like being a part of everyone else’s stage of life, while at the same time being neatly sorted into your own category (empty nester parents here with no children, actually reading the books they brought to the beach).

Mostly, I think, it’s watching other people do the things that you have in some form or other done yourself: I watch parents hold happily shrieking small children in the shallows as waves break over their feet, and I remember those very long-ago moments when my children were toddlers and my own hands were enough to guarantee their safety. I watch a father entice excited but scared 8- and 9- and 10-year-olds into the ocean and educate them in the art of jumping waves and I think about my husband whose favorite holiday activity this is, explaining over and over when you ride over the wave, when you dive under. And then I’m also watching the people at the stages I haven’t reached yet — the grandparents with grandchildren, even a great-grandfather we met in the water, while his first great-grandchild was up on the beach, probably under one of those special baby sun-tents.

I look at the burdened parents, trudging down the dunes with more tents and Frisbees and paddle ball games and boogie boards, and that isn’t even to mention the folding chairs and the coolers and the extra clothes in case it gets cold later on, and whatever you do don’t forget the five different kinds of sunscreen, and I know exactly what getting out of the house (or the cabin or the motel room) was like that morning. I have so been there.

Every day as we (metaphorically) skip down the dune, carrying only a chair apiece, an umbrella, a beach bag, and a book bag, I feel as (metaphorically) light and spontaneous as could be — give me my novel, my spare novel (in case I finish the other one), and my virtuous hardcover work of nonfiction (came in useful the other day for hammering a friend’s beach umbrella deeper into the sand), and I’m ready to roll.

But all around us, in the elaborate encampments that families build on the sand, I see the small daily family stories and I know the parental parts by heart. Call kids back to put on more sunscreen. Start to build big elaborate sand castle projects and abandon them half-done. Wrap chilled children in beach towels. Schlep back up to the bathroom yet again with a child who forgot to mention it three minutes ago when you hiked to the parking lot to buy ice cream at the concession stand.

Partly, I think, it’s that everything at the beach is so tactile. I look around me at the parents contending with cold squirmy bodies and hot sand and gooey sunscreen and wet bathing suits and I remember it all, in my skin and in my soul.

Even the family stories that I have manifestly never lived myself seem somehow familiar here, relationships that we imagine might be at least adjacent to our own. At sunset on the beach this evening, we watched a bearded young man with a small infant strapped to his chest in a carrier; he stood at the edge of the surf, watching the baby’s mother, who was out with the surfers in the twilight. When she finally came in and handed him her board, the baby was fast asleep.

And partly, of course, it’s the immediacy of bodies. There’s no point in pretending that you aren’t sitting on the beach reflecting on what youth looks like in a bathing suit, watching the more self-conscious adolescents tug at their coverage, or the less self-conscious zone out with their earbuds in to protect them from their family groups, or admiring the he-must-be-10-years-older-than-we-are Father Neptune figure with the splendid dripping mustache who comes striding up out of the rolling breakers.

I remember my own children so clearly on the beach, and part of that is remembering their bodies. Remembering their increasing physical skill as swimmers and wave-jumpers and Frisbee tossers, remembering the cumulative humor, good and bad, and the transcendent schlep of family vacations. A little boy shrieks to his older brother to come bury him in the sand, and even as I know this is going to end in tears, one way or another, I half expect to see one of my own children galloping back across the sand, with not entirely kindly intentions.

Where else are you up close against so many other families, negotiating the elements (earth, air, water, fire, if you will, in one form or another) according to their ages and stages, all of us in our private family groups, all of us on display? I don’t miss the literal load I used to carry down to the beach, but there are moments when I miss those earlier stages of family life, and when I am glad to find those remembered children, with their remembered bodies in their wet bathing suits, keeping us company and staying close.