Another spell of sheltering in place; a comfortable retirement that has gone on long enough to seem like a way of life; a lengthy education in the humanities and a long career of reading good books and talking about them with young people, which the state paid me to do (such a deal!); the thoughtful winter walking season, with its wider landscape revealed by leafless trees and undergrowth; the winter stars, Orion and his companions, so much brighter than the stars of summer; the approaching end of my eighth decade.

All of these gifts and accidents and immutable natural facts encourage reflection.

I've been reflecting on the big questions since a summer day in my seventh year when, sitting on my grandparents' screened porch and looking out at the wide world, I asked myself, just what is going on here? After a year of first grade, I had learned that, though I was the center of the world, everyone else in my life was the center of the world just like I was, and so why was I myself, this red-haired freckle-faced skinny kid named Michael, and not my cousin Grant, or my friends Keith or Marcy?

If my life was a movie, as I sometimes thought, then everybody else was in their own movie, and so just what in the world is going on? Then my grandmother called me to lunch, and my mother called me home to mow the lawn, and my question went unanswered.

For many decades, the Next Thing, school and marriage and career and family, called with an urgency that left little time for reflection. Now I have all the time in the world, and the Next Thing has lost its urgency: writing in the morning or not, a nap after lunch or not, a walk in the afternoon or the evening (my cardiologist has decreed that there be no "not" about the daily walk).

I have time to make some sense of my long life, to wonder what my life might have been had I taken the other of the many diverging roads that I've encountered. To wonder, with my 6-year-old self, just what in the world is going on here.

So today I take an evening walk, not one of the strenuous, cardiologist-prescribed aerobic walks but the every-other-day thoughtful mosey I allow myself. Leaving my house, I cross the street to the park by the lake — my lake, I think of it, having a full view from my living room, a lake view without the lakeshore taxes, though I share my portion of the shore with picnickers and volleyball players and children in the playground.

There are a half-dozen parka-clad laughing and shouting children playing in the playground, their parents on sideline benches giving encouragement or admonition, or on their phones or lost in thought. I remember watching my own children play in the Van Cleve Park playground in Minneapolis, looking forward through a long slow afternoon to an endless future moving ever so slowly toward the present. And I think of my children now, in their successful careers and life-partnerships in Minnetonka and Auckland, nearly twice as old as I was when I watched them play, and I wonder where the time has gone.

Looking ahead, the days, months, years seem slow and endless; in retrospect, they are gone before we know it:

Where are you going, my little one, little one?
Where are you going, my baby, my own?
Turn around, and you're two; turn around and you're four;
Turn around, and you're a young girl going out of the door.

Resisting an impulse to tell a young mother to get off her phone and be with her children because they'll be gone before she knows it, I mosey on along the south shore of the lake. Most of the birds, waders and paddlers, have departed for warmer climes but will be back in the spring. After all we've done to the planet, Nature is still graciously doing her thing.

And for all this, Nature is never spent.
There lives the dearest freshness deep down things,
And though the last light off the black west went,
O morning, at the brown brink eastward, springs.

At the southwest corner of the park stands an immense cottonwood tree, shading the smaller playground, its leaves whispering multitudinously in the wind all summer long. Now its bare branches reach high into the sky, 50 feet or more. I've been told that every tree we see has an equally large tree of roots underground, below the frost line, where the life of the tree, the sap that is its blood, spends the winter.

The ancient Egyptians believed that this underworld, the Duat, was beyond the reach of living humans, and that its ruler, Osiris, personified the mysterious nature of the world and the coming into being of all things. A nifty idea. The Greeks believed that trees were inhabited by dryads, minor feminine deities. I imagine the dryad of this big cottonwood spending the winter in the Duat with Osiris. See you in the spring, Lady.

Now I'm on the west shore of the lake. The people who live here have to rise early to see what we east-shore dwellers see every evening, the sun at the edge of the world. In the gathering darkness I see red Mars climbing the eastern sky, and Jupiter and Saturn close together in the sun's last light, closer together than they've been since the 13th century; four of the eight planets in my sight, including the one I'm standing on.

The night sky always reminds me of the earth's demotion in recent centuries from the concentric center of the universe to third rock from our average sun to denizen of a minor arm of an immense galaxy — my late astronomy mentor Chuck Long said that if the Milky Way, our local galaxy, were imagined as stretching from New York to Los Angeles, our solar system, out to the orbit of Pluto, would be about the size of a silver dollar — and this huge galaxy with its hundreds of billions of stars is one of a trillion galaxies in the universe. In Carl Sagan's words, our earth, with all it contains, is an inconsiderable speck, lost in the glare of its star.

Then I remember flying in a small plane over Sioux Falls in the snowy winter of 1969. To avoid airliner traffic, we took off to the north, away from the city. The landscape was an immense whiteness merging in the distance with the sky. Small dark smudges on the landscape were farmsteads, larger smudges were small towns. Clear of traffic, we turned around, and there was Sioux Falls, a larger smudge in the vastness.

So much of what I cared about in this world, my baby daughter, my wife, my friends and colleagues, my career, were all down there in that smudge I could hide behind my thumb.

Then, when we were directly over the smudge, Sheldon put the plane into a shallow dive. Suddenly, the smudge was immense, and intricately, multitudinously detailed; streets and houses and cars, people on the streets. A paradigm shift, if you will, explosive. And then I saw my house, and I imagined my wife at the sink, peeling potatoes for dinner, and my baby daughter sleeping in her crib or maybe playing with her perfect toes.

I had passed the border from Carl Sagan's macrocosm to our human world, the mesocosm, Middle Earth, as vast in our human experience as the universe is in our imaginations, and full beyond imagining of exquisite detail. And beneath this human world a microcosm that may go downward as many degrees of magnitude as the universe goes outward. And here we are, once again in the middle of everything.

Back in the present, looking across the lake, I see the lights of my house reflected in a patch of open water. All is well. I pass houses decorated in celebration of the birth of a son and the annual rebirth of the sun. Warm houses, warm light. Earth's the right place for love, as the poet said. I don't know where it's likely to go better.

Michael Nesset lives in North St. Paul.