Everest, the world's highest mountain, commands unlimited respect but no love. Just ask Edmund Hillary.

"I don't know anybody who has a feeling of affection for the mountain," says Hillary, the New Zealander whose expedition in 1953 was the first to reach the pinnacle of the 29,028-foot (8,848-meter) peak on the Nepal-China border.Hundreds of men and women from many nations have climbed it since. Many have died trying. None has come back the same. For everyone who survives, it was a supremely difficult ordeal physically, mentally and emotionally.

"You spend three months of your life, travel halfway around the world, play havoc with your health, lose maybe one of the best friends you've ever had," says Phil Ershler, an expedition member in 1982, 1983 and 1984, "and you can't help eventually but to sit down and contemplate: `Was it worth it? Would I do it again?' "

"It's a beautiful place, but it's in the same moment like hell," says Reinhold Messner, a famed German mountaineer who climbed Everest twice, in 1978 and 1980. "It's a dangerous place."

"You could climb it three times, five times, a hundred times," says Larry Nielson, a team member in 1982 and 1983. "You don't conquer it, you survive it."

Hardest of all is losing a comrade who doesn't survive it.

Marty Hoey, a skilled woman climber, was a member of the 1982 American expedition. On a cloudy, windy day, she and Jim Wickwire clung to a rock as Nielson and Dave Mayer were putting in a fixed rope above them on a steep ice wall.

"I saw Marty stand up and over onto the fixed rope," Nielson recalls, "and then the clouds sort of came in and the clouds kind of drifted off and Wickwire was the only one that was there."

Hoey had reached for the rope, missed, slipped out of her harness and plunged to her death. "It's like you know this can't be happening, and yet it was," Nielson says.

At the start of the expedition, members had agreed that anyone who died would be left on Everest. Hoey's body was not recovered. Her companions built a stone marker and held a memorial service for her at the mountain's base.

"Marty knew that you always doubled back the seat harness, but there are times when you're without oxygen and are not thinking correctly - `oxygen-dumb,' we call it," says Lou Whittaker, another team member.

"Your body will adapt to an elevation of around 18,000 feet (5,486 meters), but above that, you die a little bit each day."

Tough, resourceful Sherpas, Nepalese Himalayan people, provide logistical support for all Everest climbs. In 1978, Messner lost one of his best Sherpas in an icefall.

"When somebody dies, it's hard, it's a shock, but you don't think how it could happen," Messner says. "It happened." Second thoughts come later.

British climber Chris Bonnington describes two kinds of fears. The first is fear for oneself, a warning signal in a dangerous situation.

"The second fear, which I find much more difficult to cope with," he says, "is fear for others."

Hillary finds that "fear can be quite a stimulating factor. If you overcome it, it enables you to do things often far beyond what you thought was feasible."

Reaching the top of Everest depends partly on luck, admitted Barry C. Bishop of the National Geographic Society, who was one of the first Americans to make it in 1963 as a member of the team led by Jim Whittaker, Lou's twin brother.

"You've got to be in good physical shape," said Bishop, who died last year in an automobile accident. "But more important, it's a matter of how badly do you want it mentally."

On Everest, physical and mental shape can dissipate quickly, for many reasons.

"Some people already will be sick by the time they reach base camp - eating the indigenous foods and getting those 3,000-year-old bacteria in the stomach," says Lou Whittaker.

Altitude, wind and cold are more dangerous enemies.

"Every climb I've been on," Whittaker says, "some people have broken ribs from coughing. The atmosphere pressure is so low up there that a hard cough will break ribs."

Tim Macartney-Snape, an Australian veteran of Everest expeditions in 1984 and 1990, says:

"One of the first symptoms you get, apart from the breathlessness of being at altitude, is the nagging headache, usually in the back of your head. People become irrational."

Pulmonary edema fills victims' lungs with fluid at high altitudes and, in effect, drowns them. They easily can be saved - if they're immediately evacuated to lower elevations.

"Without oxygen," says Whittaker, "the fire goes out inside you." Extremities don't get enough oxygen, so toes and fingers are the first things affected.

Bishop learned that the hard way when frostbite forced his emergency evacuation from the mountain and he lost his toes.

"You know it's happening," he said, "and you particularly know you're in trouble when that increased pain or discomfort in your fingers and toes stops."

Nielson, who lost the tip of a thumb and part of two toes in 1982 after four icy days at 25,500 feet (7,772 meters), recalls his evacuation with disdain:

"It makes you feel like an idiot to be carried out from a mountain. I've never had a situation where I couldn't get myself out."

Bonnington, who tackled Everest four times in the 1970s and '80s, says that the key to successful climbing is "to listen to your instincts." When "your instinct says to turn back, then you should turn back."

On his final summit attempt in 1990, Macartney-Snape pushed himself beyond his physical limits.

Shirtless inside his tent, despite wind-driven snow outside, he said: "My legs start to shake and feel like 100-pound (45-kilogram) weights . . . they're shaking so much they're making me feel hot."

Nielson describes a long list of disabling problems during a 1983 climb: "I had an ulcerated toe with the bone showing, and an intestinal parasite; I lost 35 pounds (16 kilograms) in five days going to the summit.

"I had a clogging in my throat, and so to breathe I broke two ribs; and then a pulmonary embolism - just below the summit, where I was throwing up some blood."

Some of the experts agree that when the summit nears, the mind seems to supersede the body.

"The mountain filters out some people, and others go forward," Bishop said.

"I think what happens to you at high altitude is the more sophisticated levels of your brain . . . the conscious part . . . is greatly shut down as conditions get tougher and tougher," Macartney-Snape says.

"And as that happens, this other part of you . . . what I'd call our sort of 2 million-year-old part of ourselves, comes to the surface a bit more, and it's almost as if during that period there's two of you."

Once a climber is on the summit, standing under a dark blue sky and looking endless miles (kilometers) into the mountains of Tibet, the agony ends.

"It's difficult to really understand how important it is to be there, and I know instinctively I really wanted to stand on the highest point of Earth, as I think most climbers do," says Bonnington.

"The greatest thing about Everest is in people's minds," says Macartney-Snape. "It will always be an enduring symbol, a symbol of hope and striving, achievement of this great journey that we are all on."