ROSS AND I BACK OFF all the way to base camp, sing Johnny Cash songs around the campfire for a couple of nights, then attempt Nyambo's south ridge.

The first 2,000 feet are an unbelievable briar patch of rosebush thorns and cactuslike stickers. It's so steep I fall backwards and smash my right forearm. When we finally emerge onto the alpine slopes above, we're so scratched and bloodied, we'll be pulling spines out of our hands for the next month.

We dig camp into the rocks at 15,000 feet. The wind is fierce, and we resort to lining the inside of the tent with brick-size rocks to keep it—and us—from being blown into the sky like Dorothy's house in The Wizard of Oz.

The next morning, our second summit bid is no less dicey. We dislodge boulders that career frightfully through space. We climb sideways and down and over and sometimes, when we're lucky, up. The weather is splendid and, despite my bruised arm and a nasty wind, I think we have it made.

Then, somewhere above 17,000 feet, Ross slumps to the ground. His legs refuse to go any farther.

I ask him to sit tight and rest while I recon above. I climb up the arête, crisscrossing through a maze of stone turrets, entranced by the terrain. My progress is eventually stopped by an overhanging stone face I can't scale without a rope. I climb back down to Ross, hoping he might have recovered his strength, but his face is ashen. We have no choice but to descend.

I don't say anything to Ross, but I'm burning with that agonizing, compulsive need to stand on the summit. I secretly, perhaps foolishly, decide I'll solo it.

Once Ross is safely back in the tent, I march off along various spurs to inventory my options. I sit in the buffeting wind and move the tiny, circular window of the monocular up and down every possible route. All the rock is rotten, the glacier a spiky ocean of seracs, the summit a minefield of hidden crevasses.

Ten years ago, little of this would have mattered. Ten years ago, my drive and ambition would have gotten the best of me and I would have gone on regardless. But something inside me has changed. I sit on a frozen promontory and study the lines of Nyambo Konka, and somehow the risks just don't seem worth it. Thoughts of my daughters and my wife, my friends and my community and my climbing partner, overlay my view of the mountain. This has happened to me before, but usually I've been able—for better or worse—to put these distractions aside. This time I can't. I seem to have lost my single-mindedness of purpose, and I feel disappointed in myself.

Right up until sundown, I desperately search the south side of the mountain for a route to the summit that I can justify soloing, but I find none. On my first visit to Tibet, in 1984, I was willing to do whatever it took to reach the top. Now, I've learned, I'm not.

But I'll be back. It's who I am. Nyambo Konka is not the hardest or the most dangerous mountain on the planet. It's just my peculiar challenge.

Striving for superlatives is part of human nature—the highest, the longest, the deepest. But now that many of these goals have been reached, the future of adventure lies in more subtle, more discriminating endeavors: the most beautiful, the most technical, the project accomplished with the most style. Adventure will be less about simply surviving and more about performing with grace and virtuosity. More personal, more internal, just you and your dream.

Adventure has always been about discovery, but because we and our world are constantly evolving, what we discover is, and forever will be, something new. The golden age of adventure is upon us. Now go.