"Good morning, Merry Sunshine," says Amory Lovins, ambling into the kitchen on this, a faultless Colorado morning in July, the third morning we've met to talk. (It's best to catch him early before he pumps up the pressure in his fire hose with a mug of jasmine tea.) In college he was a whey-faced, 119-pound rail; now, at 43, he has bulked out to a portly 172. A black mustache offsets the hair that has vanished up top. He has warm, brown eyes behind 20/2,000 glasses. His manner in middle age seems almost cherubic, with no trace of what his critics used to call a haughty air. He always carries a whistle, a knife, and a piece of string (he once invented a new knot, a cousin of the Eskimo spear-lashing).

Proselytizing, teaching, launching forays against the old thinking, Lovins is still in the vanguard of the energy debate, leading the revolution from the hills. He does not have all the answers, much less pride of place among policymakers. (The Bush administration's new energy plan, he says, is "the most cretinous we've had in a long time.") But today many of his former adversaries in the utility industry provide his bread and butter in the form of consulting work, and with the calculator that sleeps lightly in his right shirt pocket he is still defining and shaping the frontiers of energy policy.

"Have you had your back cracked?" he asks.

Suddenly he is hoisting me onto his back, supporting the full burden of my body on his faulty knees. Lovins has always been helpful to jour­nalists, but this seems beyond the call.

As he's pretty much been dreaming up ideas, estimating the potential of technical "fixes," and researching and writing letters, reports, and books for 12 to 18 hours a day, seven days a week, for the last 20 years, is no exaggeration to say that his life is his work. He's gone to great length to marry the two, in fact. Lovins's morning commute is as energy­ efficient as they come. He lives in the west wing of the 4,000-square­-foot, scalloped-stone "bioshelter" he and Hunter built for half a million dollars with the help of a hundred volunteers. The Rocky Mountain Institute, where floor-to-ceiling bookshelves hold one of the world's most comprehensive energy libraries, is lodged in the east wing. The north wall of the building is backed with earth, and the sun-facing south side commands a handsome prospect of pasture, range, and mountains up the valley of Snowmass Creek Road. A large greenhouse under a canted glass roof serves as the building's solar furnace. The house is so quiet that Lovins designed a waterfall to provide a wash of white noise and to help irrigate the indoor garden. A Japanese waterfall tuner adjusted the stones in order to change the splash frequency from the range of beta waves to the more restful frequency of alpha waves.

After the impromptu chiropractic adjustment, my back feels better. Lovins brews his morning tea. He's recovered from the injury he suffered in New York last month when he tore a shoulder ligament. His speech on efficient water use before a gathering of Hudson River activists at the American Museum of Natural History was but one stop on a typical multicity tour. As usual, he was hauling some 45 pounds of low-flow shower heads, compact fluorescent light bulbs, and recent publications in a shoulder bag. Torn ligaments are one of the occupational hazards of the crusade.

"Have you seen our new paper on electrical efficiency in Scientific American?"he asked. "And here's one from Fine Homebuilding on energy­efficient technologies for the home. Here's one on abating air pollution at negative cost with energy efficiency. This one's on the negawatt rev­olution, and this one's on making markets in resource efficiency. It's very interesting now: Utilities are realizing they can treat negawatts, or elec­tricity they save and don't have to make, as a commodity, like copper or pork bellies, and trade them with other utilities."

He handed me a few more papers. If he'd thrown in one of his Heat Mirror glazing samples, one of my ligaments would have torn. By now he was surrounded by admirers, acquaintances, and people with questions about architectural fee reform, fluorescent dimmers, and the optimal pitch of sewer pipes. He fielded them all. When the crowd dispersed, Lovins whipped out a wallet photo and asked, "Have you seen my daughter?" It was a picture of a dog—Nanuq, his beloved white bull terrier.

Now Nanuq is snoozing by the baby grand piano. Visitors are constantly comparing her to Spuds MacKenzie, which seems to pain Lovins a little. He has calculated that when Nanuq runs around she emits enough radiant heat energy to raise the indoor temperature by a fraction of a degree. Sometimes he uses her to get a reading on a stranger. My first day at the house, he'd plunked "the beastoid" on my lap and given me the "beastoid compatibility test." Nanuq entertained my pleasantries with mild disdain before allowing herself to be ceremoniously returned to the floor.

There are in Lovins vestiges of the gifted but socially awkward adolescent, eager for contact but not sure of what behavior is appropriate. He's always giving his staff spur-of-the-moment shoulder rubs, but most everyone who knows him says he is incapable of small talk. A few nights earlier we'd attended a barbecue thrown by the Aspen Institute. It was after a seminar on energy policy, and we were standing in a clearing of tall spruces with Roger Sant, a former Ford administration official and the first person in the history of the U.S. government to head an energy conservation department. James Schlesinger wandered over. He'd been secretary of energy under Carter when Carter was quoting Lovins's work; Carter had arranged for Schlesinger and Lovins to meet. If they'd ever had a common wavelength, it wasn't evident, because a certain tension seized the conversation. Somehow the awkward chitchat lighted on the subject of hell, and Lovins piped up: "I once calculated a theory showing the thermodynamic properties of Dante's Inferno. If hell's entropy is decreasing and you assume that hell is infinitely hot and stays that way, then there are between hell and us a number of discontinuities with the properties that Dante ascribed to the intermediate rings."

There was a long pause. Everyone seemed at a loss for words. Except Schlesinger. He eyed Lovins with a mixture of skepticism and amusement and asked, "Has this work been published?"

"No," said Lovins. "Where would you suggest?"

"Modern Language Quarterly," said Schlesinger.