The 22,834-foot Mount Aconcagua in Argentina one of the most accessible of the highest peaks in the Andes.
Day 15: Summit (22,834 ft.)
Actually, we hadn't been close at all. we had turned back at the bottom of what would prove to be the most painful part of the climb. On our second attempt, two days later, it was still a mad dash to get my equipment together, but I was nowhere near the gong show I was the first time around. The additional two nights at 19,200 had done wonders for my acclimation, and I felt far stronger. By 8 am we reached the previous turnaround point. My head was relatively clear, the weather was perfect, and I was in good spirits, buoyed by my erroneous assumption that the top was only a couple of hours away.

From our previous high point we traversed for an hour and a half across a steep, snow-covered scree field to reach the bottom of the Canaleta, the rocky gully that guards the final approach to Aconcagua's summit. Though it represented less than 1,000 vertical feet of climbing, it took nearly three hours of grunt work. The whole thing began to seem like a purgatory I'd never escape, as I tried to sync my pace to the steady flashes of Viesturs's yellow climbing boots in front of me. My feet kept up their obedient march, but looking down, they seemed not to be my own. My head felt as though I'd spent the morning doing whippits rather than climbing.

Then, shortly after noon, Viesturs and I turned a corner and scrambled over a few boulders. We were there, on the windblown summit plateau. I had done it. Standing on the top of Aconcagua, I felt – to use the word I'd scratched in my notebook at the time – "loopy." I had hardly eaten anything all morning. After an unsuccessful attempt at a handful of almonds, all I had managed to put down were some M&Ms and a few Oreos. The bulk of my calories must have come from the Kool-Aid that I'd mixed into my water bottles.

"How's that feel?" said Viesturs, as we stood on the summit.

I didn't have an answer. Looking back at the photos, I see I'm flashing a wide smile – a rare thing for me – but it seems filled with relief more than triumph. The entire journey, in retrospect, was a series of anxieties, alleviated one by one: My feet held up, I did all right in the thin air, I didn't hold the team back. As it all started to fall into place, I had begun to relax and gain confidence, letting the rhythms of the climb and the physical exertion quiet my racing mind and focus me on the goal. The relief of standing on top of the continent was confirmation that all the work had been worth it. And it had been hard. The summit day, which, with the descent, stretched to 14 hours, ranks as one of the most physically and mentally challenging of my life.

During my time on the mountain my head spun with inordinately rosy visions of life back in New York, and, after I returned home, I reveled in the joys of reentry: my extra-soft bed, my luxuriant daily showers. Back at Base Camp, Peter had said that mountaineering was a lot like being hit in the head with a hammer: It feels really good when you stop. But as my head once again gradually became cluttered with the detritus of modern urban life, I began to understand why men return to mountains again and again. My thoughts drifted back to the emotional highs and the sense of accomplishment (hindsight is metic­ulous at censoring the unpleasant), but mostly to the mental clarity, that special focus born of high-stakes endeavors. It reminded me of something Dave Hahn told me that could only be fully understood now that I had Aconcagua in my rearview mirror. "The big mountains," he said, "have a powerful way of organizing your mind."