As if by fiendish design, the highest points on earth loom tantalizingly at the limits of mankind's physiological reach. Mountaineers and M.D.s agree that above 8,000 m (26,246 ft.), a physical curtain begins to fall. Higher than this, the air is so thin that ordinary people can live for only several hours -- if at all. Trapped in the so-called death zone, says one climber who is familiar with these altitudes, "you can't shout for help anymore. You lose your sense of logic. And you die in euphoria, overestimating your own strength."
Only 14 summits, all of them in the crescent of mountains that runs from northern Pakistan southeast along the Himalayan chain to Sikkim, exceed this mysterious boundary between life and death. To climbers they are known as the eight-thousanders. And many of them, including Mount Everest, were conquered by mountaineers who fudged a little: they used bottled air. No one had ever conquered all 14 -- much less without oxygen -- until last week, when Reinhold Messner, 42, a brash, blond-bearded native of Italy's South Tirol, stood triumphantly atop Lhotse, the world's fourth highest mountain. Having conquered 13 other eight-thousanders in the past 16 years, all without oxygen, Messner had completed mountaineering's grand slam.
The sport's acknowledged master began knocking off the highest mountains in 1970, when he scaled Nanga Parbat (26,657 ft.) in the glacier-shrouded western bastion of the chain. Then he climbed Manaslu (26,781 ft.) in central Nepal and Pakistan's Gasherbrum I (26,470 ft.) with Peter Habeler, a longtime climbing partner. In 1978 Messner and Habeler, now 44, climbed oxygenless to the summit of Mount Everest (29,028 ft.), and the mountaineering world gasped. In 1979 Messner went back to the Pakistan-China border and conquered K2 (28,251 ft.), the world's second highest mountain, and, to top that, lumbered up Everest again in 1980, this time all by himself.
After climbing three more, Kangchenjunga (28,169 ft.), Gasherbrum II (26,361 ft.) and Broad Peak (26,401 ft.), it seemed that he had exhausted the possibilities. Or had he? "It was in 1982," he says, "after my hat trick, after the first time I was able to climb three mountains in one season, that I understood it was easy, or at least it was possible, for one human being to climb all the highest mountains in the world, all 14 eight- thousanders, in a lifetime."
It has not been easy. Last month Messner made three separate attempts to conquer Makalu (27,765 ft.). On his last try, he told TIME in a radio interview from base camp, "you could do 20 to 25 steps, and you had to stop for a while and breath deeply ten to 20 times." Last week's triumph on Lhotse * took only one attempt. Delayed an hour by adverse weather conditions, Messner and Partner Hans Kammerlander gained the summit with a moderating wind at their backs.
In Europe, especially in West Germany, Messner is a media darling, with an ebullient personality to match his outsize ambitions. He is the author (without any ghost) of numerous magazine stories chronicling his exploits, and he usually carries the photo credit as well. In addition, he has written 24 books, which have sold roughly 500,000 copies worldwide.