"I could not rest until the topmost stone was beneath my feet," said John Muir. That's right, nature-loving boys and girls: John Muir was a peak bagger.

Long celebrated for his founding of the modern environmental movement and his exuberant love for the small wonders of nature -- "not a sparrow falls to the ground unnoted" -- he is perhaps even more accomplished as a climber.

His books and letters are filled with wild scrambles, first ascents that reveal him to be a serious peak-bagger, and frantic, non-stop marches to distant summits before night or thunderstorms closed in. According to a new biography by Graham White, he was "the greatest climber in America during the last quarter of the nineteenth century. He scaled dozens of remote peaks and achieved first ascents of Mt. Ritter and Mt. Whitney years before mountaineering existed as a sport ... in America."

I was thinking about John Muir a few weeks ago while in the San Juan Mountains of southwest Colorado, where I climbed two 14,000-foot peaks, Redcloud and Sunshine. There are 69 "fourteeners" in the continental U.S. (54 of them in Colorado) and dozens of clubs and Web sites dedicated to the pursuit of climbing them. Mostly, I was thinking about the two very different ways to enjoy the mountains: peak bagging vs. relaxation and solitude. I love both dearly and equally, as I would two children. And like two children, they rarely get along with each other.

It's a guilty pleasure, peak bagging. Among many backpackers, its practitioners have a reputation for being rude, condescending and not caring for any part of nature that isn't the highest ground. When I'm on such a trip, I often just tell friends that I'm going "camping."

Starting at first light, I make it up Redcloud by 9 a.m. Sunshine Peak, at 14,001 feet the most modest fourteener, beckons a mile to the west, but it's already clouding up, and the forecast is thunderstorms. Absurdly, if Sunshine were just two feet lower, I would not attempt the climb. If the foot of King Henry I, on whom we have ostensibly based the measurement, had been 1/100 of an inch longer, I would not think of risking it, as Sunshine would be (I did some quick calculations in my head) only about 13,900 feet. Clearly, the wise choice is a rapid descent. Instead, I run across the saddle, scramble to the top, and then descend as fast as I can, berating my stupidity but sky-high on adrenaline and endorphins.

The mountains are different today than in John Muir's time, when climbing any mountain was always a solitary wilderness experience. Today, routes up all the fourteeners are like cattle trails. The trailheads get packed with cars, and the summits become more crowded than the mall -- all while thousands of square miles of high country within plain sight remains untrodden.

Ask a member of the "Fourteener Club" if he or she has ever summited Grizzly Peak, 13,988 feet, and you'll probably get a blank stare.

In one respect, I'm glad the high peaks act as Gore-Tex magnets. On trips when I steer clear of the major peaks and trails, I know I can find oceans of empty country. Surrounded by "thirteeners," I won't see another soul and can lie back in an alpine meadow, key out wildflowers, and watch the clouds sail over the high peaks.

Many years ago, I climbed Mount Rainier with two friends. But instead of the Muir route by which the long lines of roped and guided hikers ascend, we went up the Cowlitz Glacier, a more technical undertaking. We picked our way around crevasses in a vast, blue, black and white sculpture garden of ice, rock and snow. Except for the sound of our breathing and rhythmic, crunching footsteps, it was mostly silent.

Then we crested the top, and found ourselves in something resembling an REI tag sale. More than 50 people in fluorescent yellow, red, orange, and green parkas covered the summit. Climbers were laughing and shouting, taking their turns standing and snapping pictures on the small mound that formed the actual summit. We waited for a break in the crowd and scurried over to have our minute on top before giving in to the friendly but impatient stares of the next group.

Back in our private world on the descent, I wanted to stop and sit, to burn a mental photo of the weird shapes. But the day was warming, and rock and ice were starting to break loose from the slope above. A few melon-sized boulders whizzed by. Without a word, we kept moving.

Steven Albert is a contributor to Writers on the Range, a service of High Country News (hcn.org). He is a wildlife biologist in Zuni, New Mexico.