Air conditioning is a wonderful advance in national comfort, no doubtof it, but like most good things it has drawbacks that can be serious.

I don't mean simply that idiots will of course use air conditioning to get a room to goose-bump levels of cold that would not be tolerated in winter.

The bad thing about air conditioning is not that it can be abused but that it can be used reasonably and correctly. Its very virtues can be an obstacle to deep understanding.

To work comfortably all day in a modern office is such a benefit that nobody would want to return to the days of sweat-soaked shirts, wilted seersuckers and edgy tempers, so what good can possibly be lost, you may ask, by turning on the air conditioning?

I remember some years ago living at Dupont Circle on the fourth floor of an old house that had high ceilings. We had only one room, a huge one into which a kitchen and bathroom had been fitted. A Palladian window framed a superb view of the fire engines that came about twice a week to put out small fires in our basement. Everybody would go out on the street, then return when the firemen left. Because the roof was not shaded it never quite cooled off, though usually by 10:30 p.m. the room was cool enough to support life. Before that, one could sit on the fire escape.

There was a wooden chest in the kitchen that held a 50-pound lump of ice. It was called an icebox, children, and it kept milk cool enough to prevent souring, usually. The iceman lugged the ice up the endless stairs and put it in the icebox once a week. On Friday evenings the ice lump was about the size of a fist and, as the new block of ice had arrived earlier, the small lump could be cracked, put in two glasses of tap water and, wow, you had instant ice water.

It was something any young married couple could look forward to all week.

But now I just reach into that plastic box in the freezer and grab a few ice cubes. It's been ages since I looked forward to Friday night ice water. Much has been gained over the years in the ice department, but also something has been lost quite apart from youth.

Also, I noticed ages ago that if I worked all day in farm fields along the Lower Mississippi I was surprisingly comfortable. Everything was cotton, and even without a breeze the air continually cooled the sweat. When the sun got low it was a sensuous matter to swim in the farm lake, even if the water was 86 degrees and the lake surface covered with fuzz from cottonwood trees.

Not for a minute do I say there is total merit in a life of physical discomfort. If I thought so, I'd pitch out our electric icebox and get a job in the fields of Southside Maryland.

But I cannot help noticing summer is different now. It goes too quickly.

All too soon, about Aug. 20, something new is in the air, even if the weather is still hot. A hint of fall is about, and the best bugs stop singing in the sundown air. By Labor Day, which is often hotter than hell, you realize summer is over. Summer is opulence, not just heat, and it ends in August.

And what if you have not really experienced it? Even with air conditioning, everybody experiences uncomfortable heat in summer. But we no longer have that long spell when our formerly protesting body has finally yielded to July. We dabble with summer nowadays and sometimes fight it, sometimes try to sneak past it, but no longer sink deeply into it.

I think one can try, at least, to strike a mean by which you accept cold grocery stores, cool offices and public buildings, but still experience much of the summer when not in those places.

I once had a big convertible that had air conditioning. Of all dumb things. And that dumbness is spreading in America. Now I would not have, and don't have, air conditioning in the car. Nor have we turned on air conditioning in the house thus far. Sometimes we do, in some summers, usually for a couple of days at the end of August.

We sometimes sleep with the ceiling fan going all night on low, sometimes even on high, though that usually means you have to get up about 2:30 to turn it off. The ceiling fan has a long green string you pull to start or stop it. I could make the string longer and work the fan from bed, but that has always seemed wrong. So many ethical choices in summer.

In our cities, entirely too many citizens are not only estranged but bitterly divorced from the natural world. They are no longer good animals. They live inside their heads.

"The life of the mind," as it is called, is all very well. The glory of human life. But the danger is always there, and all too often dominant, that living in just the human mind means living in a fantasy world. My wise father used to say a lot of human angst could be cured if more people sawed wood and cracked rocks, by which he meant a return to natural things.

We should go far beyond the primitive need for food and fire -- and, God knows, ice -- but at the same time we ought never forget we evolved in real summers. My grandfather used to say summer burned the impurities out of the blood. I doubt it. But I am pretty sure there is some benefit from the natural heat of summer when it is experienced for prolonged periods. Experience suggests that summer is best surrendered to and, within legal limits, wallowed in. Joseph Conrad said, "In the destructive element immerse," and it will hold you up. Something in that. You might want to turn off the cold for a spell and see.