We stuff our packs with gear and grub and ourselves into multiple layers, then unzip the tent flap to greet the first moments of morning (translation-12:01 A.M.) with an unenthusiastic whine. Chad, our head guide, is looking laudably perky, scarfing down eggs, cheese, and porridge with greedy smackings. He is full of early morning happiness that is greeted by looks of disapproval from his troops, none of whom has an appetite. I force down coffee, two snickers, some raisins, and look for the Southern Cross to conceal my nerves. The mountain is still out there, naked of life and warmth and safety. At half past midnight some unknown force launches us toward the summit of the Americas, and our dreams.

Like pack mules we plod ponderously along, hopefully upward, laden by heavy loads and breath, heads down, eyes fixed, a march of the dead. We see nothing and hear only the cadence of rock under boot. One of my snickers wants to come up for air but I will not allow it. Soon I am feeling better. Not gladiatorial mind you, but pretty pumped up. My mantra is "It's only walking." All I have to do is put one foot in front of the other. For 18 hours. Uphill. With 40% of the oxygen at sea level. I follow Chad and his pumping testosterone, and try to draw on his strength.

We stop occasionally, to rest and breathe and survey the craggy splendor. It is a perfect day. Smaller mountains recede to infinity, spangled with sunlight. We are at 21,000 feet. Only one peak towers over us now-Aconcagua-tallest peak in the world outside the Himalayas. How hip can it get? (next photo)