The fingers of your left hand, if they're still alive -- you can't see them in that crack -- are sending their messages to some dead letter box. You aren't receiving. The right hand is right in front of your face, but it's numb to the base of the palm, giving the impression of an inanimate club attached to your wrist. But your gut and legs are sending loud and clear tremolos, muscles quivering in tension and fear while you cling to granite some 60 or 70 feet above the Potomac River.

Rock climbing: the first step on the way to snow-covered mountain tops.

Mountaineering has been a sport for more than a hundred years and no one has provided a respectable rationale for it. Today most mountains are accessible by air, muting even further George Mallory's "Because it is there." Nevertheless, more would be Sir Edmund Hillarys ascend the heights every year, lining up on summits like Mount McKinley in Alaska to take the obligatory photographs.

The Potomac gorge below Great Falls is a long way from Mount Everest, K2 and Annapurna, but the scrabbling climber on a truncated cliff at Carderock or Great Falls Park shares the painful motivation of the expeditions that storm the Himalayas. Each victory over vertical distance separates the successful from those who never go.

Within Great Falls National Park in Virginia are a line of cliffs along the river, cliffs which cannot be described as beautiful except as picturesque boundaries for the torrents of the Potomac below. Climbers find them both interesting and available. On summer weekends they line the crests. In winter the rock is as cold and forbidding as the ice which streaks and pocks it. The cliffs lose a lot of their attraction, but the driven arrive anyway.

You would never have considered yourself driven by anything except a desire to survive, but somehow that urge, kept repressed for several years, has surfaced with all the necessity of breath. You find yourself up the cliff on a chiled and windy Saturday afternoon. The sun is shining -- on the rocks across the river; your cliff is in the shade. It's small consolation that you're not alone and others are scattered in their own madness along the precipice.

You try to remember the rope, must remember that you can't drop more than a few feet. If you fall, Ken Hunter, the guy in the red helmet down below, will have to take in the slack around his waist and catch you. The rope runs from you up through a metal carabiner anchored to a tree at the top of the cliff and back down to Hunter. Safe. Your head knows; your heart refuses to believe.

Hunter's red hat, so tiny down there on the rocks directly below your heels, covers his firm voice that floats above the roar of the river. He is telling you there's a good foot hold just to the right of your knee. Right. Sure.

But it is there, and you're not comfortable, but you are more at ease on the rock. You recover a faint beginning of the tenuous state of well-being-at-risk you knew before the accident that once ended your short climbing career.

Your eyes quit their desperate flitting back and forth across the rock and you're able to focus on the simple line of handholds and footholds -- ledges for squirrels, perhaps, but sufficient for your own big-booted toes. You can pause in your hyperventilation to bang a hand against your chest and wonder if it was the cold rock or your death grip that stopped the circulation.

Hunter, an expert climber, went up this cliff so nicely, generating waves of controlled movement from one good hold to another, cresting over the difficult interludes. You wouldn't have had the nerve to try it without watching how smoothly he did it. That, and that he's on the other end of your rope.

The most remarkable thing about Hunter is the degree to which he inspires almost immediate confidence. A little less than average height, he will complain of his lack of reach on certain climbs, but no one would call him short. He seems bigger than he is and moves with the grace of someone who thinks in terms of physical possibilities, not limitations. Well proportioned, he doesn't show any mass of muscle, but he moves powerfully on rock.

Direct, he pays attention when you speak, and when he wants to be sure you understand what he's saying, but there is no false bravado. His reddish brown hair and redder beard are as neat and orderly as his climbing gear. His reputation as a climber forces an expectation of bigger, more battered and obviously powerful hands, but you wouldn't notice anything extraordinary without looking for it.

An electrician in his more mundane hours, Hunter is the chief instructor of Geneva Spur Mountaineering School. He has climbed cliffs and mountains over most of the country and led expeditions to frigid mountains inside the Arctic Circle, ascending the south buttress of Mt. Turnweather on Baffin Island.

You have to get moving again before the muscles tighten, so you concentrate on the rock and go up, considering the next move and then the next, until you're almost at the top, under the overhang.

Even before the accident, before you fell so painfully and lost faith in climbing, you had never made it up anything quite this difficult. There is a way off to the right, an easier escape to flat ground. But Hunter didn't go that way.

Hunter projects no sense of testing, but because you're with him you want to do well. As a teacher he has the extra edge, past expertise and knowledge to unleash the internal drive in people to excel. He likes to teach, he says, besides the extra money, because he finds satisfaction in helping others "get safe real quick."

"I didn't have lessons when I began," he says "so it was a slow process." He had to learn safety precautions as he learned to climb. "It took a long time to get to where it was a lot of fun."

Hunter, 26, has been climbing 11 years. Having begun with a high school caving club, he soon discovered he preferred climbing under the sun and took to the open-air cliffs at Great Falls.

"It was a gradual thing," he says. "I'd gather together a little more equipment and do a little more." And gradually he discovered balance.

"Balance is the key to climbing," he says. He talks about a woman who was in her 50s when she began to climb who easily scaled routes on cliffs whee he couldn't follow.

"It took 10 years before I outdid her on rock," he says, "and by that time, of course, she was in her 60s. She wasn't strong, but she had balance."

Balance is a difficult skill to master -- Hunter says he has difficulty teaching very strong people like football players to climb.

"I usually just have to let them go at first. They have to try to force their way up. I have to let them burn themselves out until they finally see that they can't do it that way. Then I can begin to teach them the right way to climb.

"Once they develop the balance and finesse, they can become very good."

The overhang is, as they say, interesting. You're not feeling very strong or very balanced. The rock seems to be pushing you toward the void, and you wish you were as conditioned as Hunter, were able to run in marathons just for the experience, at least wish you were one of the gymnasts or dancers that he says make such good climbers. But it'll take more than a little disco to get you over the top.

Hunter teaches ice climbing in the winter, traveling out to frozen waterfalls in the George Washington National Forest with his students. Ice climbing, with its crampons and ice axes, is a necessary skill for advanced mountaineering -- glaciers and snow coat the higher peaks.

"I don't climb the rocks that much during the winter," he says. "Just when the urge gets to be too much to resist."

In the summer your hands slip with sweat instead of seeming distant relatives and there is no consolation in that thought.

When you arrived at the cliffs, looking for Hunter, everyone you'd asked had known him. You'd even been invited to climb with another group if you didn't find him, even though "if you're climbing with Hunter, you're probably a lot better than we are." An enjoyable, though unearned, praise by association.

And suddenly you're there, on top, with no real memory of how you did it, what remarkable moves placed you with the onlookers. Flushed, you hear a bit of praise: "very nice," "good climb." Leaning back over the edge you yell to Hunter, "Off belay."

You untie the rope from your climbing harness and sit down on a rock, hoping your cool grin covers your trembling legs.

For some people rock climbing in the Potomac gorge is an end in itself. They want no more than the security of climbing with a rope running between themselves, an anchor at the top, and their belayer at the bottom.

You, though, climbed with Hunter -- another step, perhaps, on the way to a real mountain.