The last run last year: Standing at the top, 11,250 feet up, taking in the glistening sheer blue of a Colorado supersky, hearing the soft rustle of hard skis on newly packed powder kept dry by the cold, thinking that a short season's sport must now be capped and shaped for a long off-season's storage in the capillaries of reflex and memory where all skiing ultimately is done. "Show me how, Milt."

Milt clears his throat and he is off on the mountain's brow. He test-changes weight from one foot to another to slightly bent knees and shuffles his skis to get the feel of the snow. I let him go a few hundred yards, nodding in telepathic approval of his command of the particular style that makes him distinguishable from other skiers half a mile away. The hill breaks; Milt disappears.

There is a fluttery moment at the beginning of every run when ski-nut draws himself up and vows that this will be best run of his life, the one combining speed and form, risk and control-the defining tensions of the sport-to a degree hitherto unachieved. I take the pledge and shove off. It is on the brow; the fronts of the skis clatter lightly and snow whips like smoke off the butts. I let arms hang loose and ski poles drag, and wiggle a bit to get set. For the pairs of skiers coming up overhead in the chair lift, which parallels the trail for a short stretch at the top of the mountain, I press ankles tight together and throw in some lazy linked turns, the end of one flowing into the beginning of the next. It is a conceit to strut like that before the hill gets bumpy and steep, and it is ever sustained by a pleasant conspiracy between the skiers in the chairs (their turn will shortly come) and the skiers on the run.

The trail is a feeder running along the spine of a ridge, and other trails drop off it towards the valley floor some 3,000 vertical feet and 10,000 or 12,000 skiing feet below. Initially the pitch is easy. The bumps, built up by one skier after another turning on the same spot, each skid pushing a little snow, are like breeze-blown waves. An eye-crinkling sun blazes off the snow. One can look down at what appear to be someone else's feet in a Martian's shiny plastic boots, and watch sleek shiny plastic skis slip in and out of the troughs, and feel the sun beating down, and almost fall asleep.

Milt is ahead, stopped at the point where the ridge trail ends in a split, watching me. In a ritual honed by 15 years of skiing together, we trade critiques.

"Nice, Milt. Together." The last is a reference to the skier's constant effort, made for the sake of easier turning as well as for appearance, to keep the two skis parallel and close as one.

"Looking good."

Our new trail, Prima, drops to the left down the shoulder of this giant mountain. Looking out, one can see only to the near crest where the trail falls out of sight. I lean incautiously on my poles, snap forward, and point my skis straight downhill over the crest, pleased at the pretense that I am going over a precipice into an immense vacant sky.On the newly steep pitch the skis accelerate sharply, and in seconds a small but welcome tinge of fear makes its warning presence felt. I skid into a turn-always the first one in a sequence is to the left-which cuts the speed and provides the instant needed for eyes to sweep the slopes to plan the next hundred yards. When you come out of a straightaway and are turning, with skis slipping sideways across the snow, you are either in control or regaining control. Unless, of course, you are out of control. The challenge is to be right up on that line.

The moguls begin: big close bumps carved three or four or more feet deep in steep slopes by successive skiers turning to avoid hazards or check speed. The tougher stretches of "good" trails have mogul fields hundreds of yards long; Prima has three or four such fields. Moguls are relentless, unforgiving bucking broncos. You must turn constantly or be thrown. Yet to make the turns whle the hill is forcing speed and your knees are being pushed into your face and your back snapped and your skis driven apart is not easy even for experienced skiers-the more so when you try to do it at speed and with a rhythm and even with some grace.

Picking a path down Prima's first big moguls, I feel my heart beating. I am focused entirely on the effort to lock my feet together, and to get my legs back under my body each time they swing out on a turn, and to keep from being pitched forward up the uphill face of each mogul and hurled back by the downhill face. I yearn to do all of this with at least some of the style of the hotshot skiers whose rubber-and-steel legs are 10 or 20 or 30 years younger than my own.

Then it happens. Suddenly, as through a secret switch has been thrown, I am into a rhythm and measure of control that is instantly recognizable as the best of my life. This is, of course, why I can remember this run as I do. Suddenly I have found the precise, previously hidden spot, just over the top of each mogul, where the weight must flow from one ski to the other in order to ensure that the turn is well made. I am "lifting," straightening my knees on that very spot, flexing in the wallow: the Rosetta stone of skiing. Suddenly I am turning at a speed and with a looseness and fluidity that made me sigh with the sweetness of bursting a personal frontier. Rocky Mountain high, indeed!

And instead of making the customary pause for Milt to catch up, I know that I cannot conceivably risk breaking the speed. He will understand. I shoot out of the moguls into a long smooth-surfaced leg of the trail where, free now of the distraction of the bumps, I can carve the turns more elegantly and let out an eye-watering speed and move into an endless up-down-up-down rhythm. Two legs are moving as one under the body from side to side the way bristles move back and forth on a painter's brush. It is literally breaktaking, a skier's apotheosis lasting for the few minutes it takes to ski a mile and a half down the mountain-lasting for a lifetime.

It is not always like this on the mountain, but the quest for new peaks of achievement and the recollection of old peaks are what make skiing the consuming passion it is. It is not just the speed or the style or even the bite of the air and the scenery and the color of the other skiers, lovely as they are. It is not even the escape skiing makes possible from the ordinary physical and emotional coordinates of one's life, dreamy as that is.The essence of skiing for me is "challenge," pushing myself to the limits of my competence and confidence, and then going a little bit-but not too much-beyond. "How was it?" I will say to Milt. "Challenging."

Past peaks are etched in my memory with the clarity of the trail breaker's lonely track in fresh powder snow: Perhaps 35 years ago, in a Boy Scout race on the narrow trail behind our Massachusetts home, I came shotting into "the schuss," or sudden steep place, and picked up speed. Unwilling to betray my fear to the few blurred spectators at the side, I clung to the hill in panic and wondered-as I wonder to this day-whether I would avoid the very large pine at the bottom on the right. Superhuman effort, not too evident to the witnesses I hoped, averted disaster. The blue ribbon stayed pinned to the wall for decades. Kids' skiing, I have since had my own occasion to learn, is the stuff of adults' terror.

In high school once I skied the Middlebury ski-jump landing hill; I was too scared to go off the jump. Landing hills must be very steep to receive descending jumpers. The instant speed made my heart jump. Until I realized, only after a few seconds, that any hill that's smooth and whose bottom is visible is (theoretically!) skiable, I did not believe I would survive. Again, the skier's essential companion, adrenaline, saved the day.

It was, in fact, only as I penetrated my 30s that the meaning of "challenge" began to change from an emphasis on terror to an emphasis on command of difficult circumstances. As my friend Judy, Milt's wife, would have it, terror is not acceptable for a family man with responsibility. Maturity commended caution-especially since I skied only one week a year-though not to the extent of entirely obliterating the warning prickles of fear. Skiing is not, after all, billiards, a game played while standing still on level ground. Skiing is an ideal sport in which to engaged in the middle-aged person's familiar ritual of testing oneself against time. There is simply not possible in other sports, where deterioration is virtually unavoidable, it is feasible in skiing to constantly improve in technique even while losing ground in strength and reflex. Indeed, to a point-the point where the body reasserts its primacy-skiing is very largely a sport of technique, of mind. Every turn you take is a practice of technique, of thinking about how to control the body: where to plant the pole, how to shift weight from one ski to another, when to begin the next turn-all the things that make the ski magazines, which are unreadable, well read.

That is why skiers are constantly studying every other skier on the hill: to check out the do's and don'ts of technique, to measure each person's speed, skill, age, sex, build, equipment, dress-all the variables-against one's own. That is why skiers flex their knees and bob their shoulders while standing in the lift line, and why they regularly talk to themselves. That is why skiing is enjoyed by many people in their 60s and older. Technique lets them fight gravity and bumps, lets them ski fun hills. As I say, to a point skiing is of the mind.

So some of my peaks-all of them nowadays-involve challenge at speeds the steel-legged kids sniff at. Fine by me. There was a particular mountain in France, with one side shaped like a huge bowl, very smooth, no bumps. With the sun behind, we hurtled off the lip, carving giant arced turns, chasing our shadows, swinging down, singing down, drinking in the sun and snow, hoping the trance would never end. The kids who like schussing-going straight down-would never understand.

There was another afternoon on the Charles Bozon, a trail named after a skier who had, a sign said, "disparutragiquement"-disappeared tragically-in an off-season rock slide. The pitch of almost the whole two-mile length was practically vertical and the trail and covered with hardpack in the good spots, otherwise with ice: an impossible run. Milt banged his knee and had to hobble down on one ski-a fantastic accomplishment under the circumstances. I concentrated on staying upright and avoiding ice. There was some flailing and falling, but under the circumstances-one is continually refiguring the ental equation that skiing is-I skied very "strong." For sheer duress the run was unforgettable and we should not have done it. For the anticipation, and delivery, of a major passage-a passage down the mountain, a passage into my 40s-the run was even more unforgettable and I could not have passed it up. Challenge may exist quite apart from fun.

Skiing is, all the same, more than striving for the peaks. Day in, day out, it is pleasure. Oh, one had bad runs, so-so days, moments when you quit trying halfway through a turn. Then you either straighten up, knowing that it looks awful and signals your failure to the gallery, or let your skis run straight down the "fall line," the line a rolling snowball would take, accepting the extra trouble your acceleration brings as a kind of penance. Ice on top of the snow, or rocks poking through, can remove the fun; they deny you the recreation skier's option-to check and turn at the time and place of your own choosing. To be skiing up to your level and to get in a jam and not to be able to get out of it because of a bad surface, produces in the first instance disgust, panic and peril, and-when it's all over-a lingering hostility to skiing.

Then there is cold, or, more precisely, cold made intense by wind. One dresses: many layers. I personally have never experienced a cold wind so paralyzing it made me vow never to set foot in whole sections of the country, like New England for three winter months at a time, but I know people who have. They wished to have it established that pain and extreme discomfort, far from being normal elements of the sport with which one should learn to cope, are abnormal and unacceptable. They can live easily, even joyously, with being thought a quitter for leaving the mountain when the wind is so cold it burns uncovered skin and makes eyes ache. To confess: I am ready, now, to have them twist my arm.

I have deliberately not mentioned what every monskier instantly brings up, the prospect of injury. There's a reason. Skiing, looked at abstractly or from a distance, has obvious dangers. Film and lore of racers, who go at speeds upwards of 60 mph where "good" falls can produce a broken leg and bad falls can be fatal, have made their mark on the public imagination. Everyone turns out to know someone turns out to know something like that. But racing is a world apart from recreation skiing, and skiing without adequate preparation (in conditioning and technique and equipment) is at least half a world apart from skiing with sense and control.

In my circle there are two kinds of falls. The first, which amounts to little more than sitting down uphill, leaves a certain tenderness but has no status because sitting down on the backs of the skis or falling uphill means you have not got your weight forward on your skis the way it should be to turn well. The second kind of fall involves falling forward or down the hill. It tends to hurt a good deal more but leaves you with the satisfaction of knowing that you were trying to ski the right way. One can fall two or three times in a single run, or go a whole day without falling. If you respect the mountain and do not aim to get out of control, survival is simply not a problem.

For all that skiing is an individual sport pitting the skier against the twin measures of his own body and the mountain, its ultimate pleasure is social. Skiing is an activity almost always done with other people-wife, children, friends-in a setting where the sociability is is enhanced and enforced by the trouble you have gone to get there, by the fact that once you are there you ski for hours and days on end, and by the peculiar nature of skiing. By that I mean that skiing is the one sport in which people of very disparate abilities can take part together and have fun. Mixed doubles in tennis is the closest thing to-but a long way from-the pleasure routinely available in skiing from sharing it with your wife.

A hill, you see, is many hills, depending on whether you take the shortest and bumpiest way down or traverse back and forth on a slower route. Either way the bottom or the places very 200 or 400 yards along the trail where you stop to collect your party and discuss the aesthetics and physiology of the stretch just skied, are at the same spot. The only difference is that I may arrive at the stopping place a bit before Barbara-the better to comment on such fine points as whether her weihgt was properly on the downhill ski and how better to navigate the hill's shoals.

Such comment, I might add, goes both ways. The truth is that skiing is mainly a sport of technique, the urge to improve is inherent in it and talking it out is an awfully good way to improve.And the talk is fun. Each slope, moreover, has its own texture and anatomy, each day its own weather and ambience, each skier on the hill has his own style and psyche: much to ponder and discuss.

Skiing offers, too, the elevated seclusion of the pairs of chairs on the lifts in which you are carried smoothly and quietly 10 to 50 or more feet above the trails and trees on a beeline up the mountain. You are within sight but not sound of fellow skiers on the lift for 10 or 15 minutes of resting, ruminating, making ready for the next run. No other sport I know has such nice built-in pauses.

And at the bottom of the mountain at the end of the day, there are the rewards of fatigue. Barbara and Judy will have made the last run or two on the lower trails themselves, while Milt and I will have caught the last chair up to seek a bit of challenge and identity at the the upper altitudes. Most mountains bottom out on a flat where you take off your skis. There is a clatter of bindings being snapped open and skis clapped together to knock off the snow. What with coming into the lee of the mountain, and the way the air softens at that hour, it is a mellow time. Among the skiers leaving the mountain there is an unspoken camaraderie and among ourselves there is the quick preliminary totting up of the day's triumphs and bruises-the obligatory full and detailed review awaits dinner-and the slow walk back in leaden boots to apartment, inn or car. Group shopping, saunas, naps, reading, perhaps a pre-cocktail Coors: all this must be beaded on a day whose final knot is a late dinner. Only once in 15 years have we mustered the energy to find some after-dinner entertainment; dancing it was. On a second effort, when we showed up at a casino in Chamonix, we were turned brought passports. We collapsed in gratitude and have not tried to survive past dinner since.

For all the sweetness of these pleasures, however, I would not pretend that they diminish the allure of those peaks of challenge. And so it is . . . late in another day and the sun is slanting in at the angle of the hill casting long streaky shadows, and the snow is blue turning gray. I slip off a traverse, and moguls like giant marbles tumble across the trail. Sucking air in sharply, I head down at a clip at which I know I will have to strain to hold on. The wind is roaring and the trees are a blur at the side and the whole world is pouring down through my legs and up from the mountain into the moving plane where skis meet snow, and again I know it is the best run of my life.