My father and I always found a special camaraderie in sports. For as long as I can remember he was my constant, patient mentor in his two great loves: tennis and skiing.

If we took opposite sides of a dinnertime political debate, or argued whether the Beatles made music, as I contended, or noise, as father insisted, we always united on the steaming asphalt of the tennis club, or on the fluffy powder of the ski slope.

Skiing brought us especially close. My father is not a man of many words, but he was always eloquent in communicating the quiet joy he felt when gliding across a slope's undulating white expanse. With each ride up the chair lift he would become positively effusive in recounting tale after tale of skiing past.

"Like the time," he would start, "I helped an Austrian ski patrol team rescue several stranded beginners on a slope that was way too difficult for them." With every ride up the mountain, my father repeated another skiing memory. His face glowed with pride.

On the slopes themselves, we had always been more coach and student than father and son. Back in the ski season of 1966, The Washington Star immortalized our relationship. The paper ran a photo of my father glowering at me for not keeping my knees properly bent. I look duly repentant.

I was also ashamed of a patch of snow that ran up and down my 9-year-old behind, the humiliating sign of tumbles too frequent to count. My father was an exacting but understanding coach. I stubbornly resisted his advice even though he had the most elegant stem-christie style on the mountain. My version always ended up with one ski crossing the other, sending me face first into the snow. At first, I found it impossible to meet my father's standards and frustration set in. He, however, persevered. Eventually I learned.

That revealing photo, now framed and hanging in my father's dimly lit study, is turning sepia. Eighteen years after it was snapped, age has robbed my father of his ability to carve up a mountain with ease. His once spry legs, which had acted as resilient shock absorbers, are now stiff. They slow his speed and dampen his spirit.

Trepidation has replaced anticipation as he approaches a tough slope. As its biting curves invigorate and challenge my 27-year-old legs, they wobble and topple my father's 74-year-old frame. The "schuss" speed of his expert youth has become the slow traverse of a cautious tyro.

On a recent trip to Vail, my skiing finally came of age, while my father's simply aged. In a way, the slopes crystallized that ineffable process known as maturing. The spirit of youth glided by the slowness of age.

Years before, I had measured my manhood by how many compliments I could pry loose from my father as I perfected my parallel style. Today, a muttered "good" or "bravo" as I slide into one "S" turn after another reflects my father's long hours of painstaking coaching -- and his hard-won love. He had done his work well and, as a painful result, we no longer skied on the same level. Our abilities had diverged like a fork in a meandering trail.

During our last ski trip, a bittersweet irony developed: The teacher with the wispy hair became the taught; the accomplished, with his stories of slope-side heroics, was transformed into the unsure; the encourager became the disconsolate. The old, clinging to a stem-christie style that seemed more tentative than graceful, relied on the young.

Before we left our hotel room on our first day's ski, my father sheepishly poked his head into my room and asked me to help fasten his boots -- or "plastic prisons," as he called them. As I bent down to help him, he recalled wistfully the "civilized" leather boots of his youth. After the final clasp snapped shut, he patted my back and mumbled an embarrassed "thank you."

Not too long ago, my foot fit snugly into his lap as he laced up my child's-size boot.

During our first lift up the mountain, my father launched into one of his skiing tales. This one was about a jump off a rock for which he received $20. A professional photographer had paid him for his daring.

But halfway through the yarn he stopped and announced that our trip to Vail would determine once and for all whether skiing held any pleasure for him anymore or whether his skis would join the rusting fencing foils and the neatly stacked wood tennis rackets in our musty basement. As we skidded off the chair, his eyes glinted with apprehension at the personal ultimatum he had just made.

We cut up Vail's intermediate-level "Ruder's Run" course into six 5-minute breaks. My father's short legs stiffened as the snow mischievously changed from billowy powder to shimmering ice. His lungs heaved. His breath grew short.

As the course grew steeper, my father violated the one rule he had drummed so insistently into me. His knees remained ramrod straight when they should have bent to absorb the hill's pesky bumps. He fell, and my heart sank with him. It wasn't the tumble that disconcerted me, but the strain that crept over his face as he tried to get up. Recalcitrant muscles were playing their dirty trick on him.

He finally got up, dusted himself off like a rodeo rider tossed aside by a bucking horse, and skied on. This time a row of moguls played with my father's balance. I heard myself whisper the very same staccato words of advice he had drilled into me so many years ago: "Bend down," "skis parallel," "up-down, up-down."

When he finally reached me, I stopped coaching. I couldn't bring myself to embarrass my father by offering him the same tips he knew too well. "It just doesn't go," he complained with a shrug, the very same excuse I offered years ago when he first stuck a pair of hickory skis on my reluctant feet.

"Give it time," I counseled, once again echoing my father's comforting, confident words.

Each day, my father stopped after our four morning runs. He was tired and often short of breath. He would plant himself at the bottom of the slope, movie camera in hand, waiting for my final sprint down the mountain. He never let me take a picture of him.

My afternoons were reserved for the tougher Vail trails, the ones with playfully intimidating names such as "Look Ma" or "Tourist Trap." After my six-hour ski day, father would sit me down and make me verbally retrace my steps, every creaky chair lift ride up, every snaking path down. He reveled in my description of the narrow chutes that forced me to tuck my poles into my waist in a poor imitation of an Olympic downhiller. He winced when I described the chest-high moguls that tossed inexperienced skiers like balsa wood rafts buffeted by frozen waves.

Each of my descriptions seemed a catalyst for my father's memory, sending it careening back to his younger ski days. He recalled how quickly he trudged up and down a neighborhood hill, in those pre-chair-lift days, often with a 25-pound rucksack strapped to his muscular back. How swiftly he cruised through ankle-high powder.

He savored his youthful abandon when he remembered how he lost control of his skis while racing along at 40 miles per hour. He ended up face first in a fir bush, unharmed, but a scary sight for all who saw him.

But this time around, I was the one with the intrepid tales to tell, with my father the rapt audience. Back on the slopes, one moment summed up how clearly we had switched parts. After my father had lost all patience with skis that flew off continually at the slightest bump, he calmly removed them and started ambling down the mountain.

I wasn't going to let him give up so fast. I trudged up the bit of trail that separated us and insisted he lean on me so that he could snap his skis back on. As he fitted his boot into the binding, a fleet skier streaked by us, leaving a trail of etched powder and the strands of a whistled melody behind him.

"That was me, 40 years ago," marveled my father, shaking his head. "God, I was fast."