WITH his high domed forehead, bushy mustache, horn-rimmed glasses, and Harvard/Oxford background, Amory Lovins is the quintessential intellectual whose idea of a vacation is sitting around thinking deep thoughts.In her worn jeans, boots, and cowboy hat, Hunter Lovins looks like the rodeo rider she is - when she's not using her degrees in political science, sociology, and law to run an international operation with high-placed connections in more than 30 countries. Despite what seem to be marked differences in appearance, the Lovinses have a singularity of purpose: exploring the interconnected complexities of energy, natural resources, and economics. Their perspective ranges from the home and family level to the global. They have coauthored a half-dozen books and share bylines on many articles and papers. The essential message: Sustainable use of resources and energy efficiency (a word they prefer to "conservation," which has a more spartan feel) can be achieved through market economics and without undue stress on the American lifestyle. But they have established different roles in their collaborative effort. Amory is research director and vice-president at the Rocky Mountain Institute (RMI) and does more of the traveling. Hunter is executive director and president, which means that she can hold up his paycheck and make him stay home to write his reports before he heads out again to "give speeches and rabble rouse," which she did recently. "I don't think I could do it without Amory and he couldn't do it without me," says Hunter, who describes her husband as "a certifiable genius who works nonstop" and has "an excruciating standard of perfection." Hunter is just as intense in her work, but is more inclined to break it off for fun. "I like to hang out with my cowboy buddies," she says. "Riding is one of my sanity releases, that and working as disc jockey and bouncer at one of the local cowboy bars." She's recently taken up "polocrosse," which is lacrosse played on horseback. RMI gets several unsolicited resumes a day from people who want to work with the Lovinses. "What we're looking for," says Amory, "are people who are literate, numerate, highly motivated, fun to be with, intensely curious, and have interests across boundaries." A small part of RMI's income comes from government contracts and private consulting, but the Lovinses purposely restrict those sources to maintain their organization's independence. They have recently obtained a grant to do conceptual work on energy-efficient transportation. "They're going right to the core of a lot of the gargantuan problems our society faces," says former Colorado governor Richard Lamm, who now heads the Center for Public Policy and Contemporary Issues at the University of Denver. "Huxley said: 'All great truths begin as heresy, says Mr. Lamm, who describes himself as "very fond" of the Lovinses. "They're heretics, but I think they'll turn out to have been prophets."