THOUGH YOU DON'T HAVE TO BE A NOBEL laureate to get to Linus Pauling's house in Big Sur, you do need ingenuity and a fondness for cattle. At the end of a long, dusty driveway—which is more like an obstacle course, what with all the gates and wandering cows in the way—Pauling lives in a small ranch house perched above the Pacific Ocean. There is no one around for miles, and only a rickety redwood deck separates Pauling from the waves crashing dramatically below. It's the perfect setting for the solitary scientist, the maverick thinker Pauling takes such lively pleasure in being.

Dr. Linus Pauling, 91, the only person ever to have won two unshared Nobel prizes—one for chemistry, one for peace—long ago earned a place among the century's great men. In 1939 he wrote The Nature of the Chemical Bond, still considered a definitive text on the force that holds atoms together; he was the first to suggest that the protein molecules of DNA might be arranged in a twisted spiral (which led to James Watson and Francis Crick's discovery of the double helix); and he discovered the cause of sickle-cell anemia. But Pauling is also one of this country's few celebrated crossover scientists, having come to the attention of the general public after World War II for his protests against nuclear weapons and again in the 1970s for his fervid belief that vitamin C can help cure everything from colds to cancer.

Twenty years later, Pauling may be getting the last laugh on the latter point. Notes MIT biophysics professor Alexander Rich, who has studied with Pauling: "He made a number of proposals that seemed outrageous, but there's been a great deal that's come out recently that lends strong support to the importance of vitamin C." Studies indicate it may stem the development of cataracts—and, yes, slow heart disease and the ravages of cancer. Last spring Pauling himself was told he had prostate cancer, but, he suggests, "it may be that my vitamin C put it off by 20 years." The cancer is now in remission. "I'm feeling fine," he says.

And he looks it. A still strapping six-footer with spots of color in his cheeks and bright blue eyes that don't miss much, Pauling wears his trademark beret atilt, and tufts of white hair stick out like cotton candy. His age is betrayed only by a quaver in his voice and by occasional forgetfulness. As he searches his mind for a name, he notes ruefully, "My retrieval lime is longer than it used to be."

It's still far shorter than the average nonagenarian's. Pauling's favorite topic of conversation remains his work; he's happy reminiscing about advances he's made in chemistry or discussing articles he's writing. But he is not prone to introspection: He has few regrets about his life, saying he's "pretty satisfied with the way fate has treated me." Fate, not God, for Pauling is an atheist. "I believe all complicated phenomena can be explained by simpler scientific principles."

Except for the caretaker, who occupies a neighboring house, Pauling lives alone on his 160 acres in agreeable disarray. surrounded by heaps of scientific journals, walls covered with honors and family photos, and shelves full of minerals (including one chunk of pyrite—fool's gold—given to him by Robert J. Oppenheimer, father of the atom bomb). He rises at 4 or 5 A.M. and goes straight to work with pocket calculator and notebook. He cooks for himself—he'll eat anything in moderation—enjoys an evening cocktail and watches the occasional Doris Day movie on TV. He still publishes 10 to 15 papers a year in scientific journals, on topics ranging from heart disease and AIDS to the interaction of atomic nuclei—work that he pursues with help from colleagues at the Linus Pauling Institute in Palo Alto, Calif., where his caretaker drives him every few weeks. Not all that work, however, is embraced by his peers.

"I say my ideas are valuable," he explains matter-of-factly. "But they're not so obviously valuable that they're immediately accepted."

This is a familiar state of affairs for Pauling. He was one of tie first people to warn—loudly and in the face of strong government opposition—that radiation could cause genetic mutations. Professor Rich sees Pauling as a scientist who was often ahead of his time. "If Linus makes a proposal based on his intuitive understanding, there's a very good chance that it will be correct. Not always—but his intuition is a good guide."

Pauling, who is of German-English descent, knew even as a child that he wanted to be a chemist, "although I never knew you could make a living at it," he says. He remembers watching in fascination as his father, Herman, the town pharmacist in tiny Condon, Oreg., mixed his potions. "I very early began to be interested in the nature of the universe," says Pauling, who devised his own minilab in his basement. His father died when Linus was 9, and his mother, Lucy, moved Pauling and his two sisters to Portland, where she opened a rooming house.

Pauling studied chemical engineering at Oregon Agricultural College (now Oregon State) and met his wife, Ava Helen Miller, when as a senior he taught a chemistry class to 25 freshman home-economics majors. "I picked a name at random," he recalls, "and said, 'Tell me what you know about ammonia hydroxide, Miss Miller.' " She knew that it was bleach, and Pauling, impressed, soon asked her out. They married in 1923, when Pauling was a graduate student at the California Institute of Technology, and had four children, Linus Jr., Linda, Peter and Crellin, all of whom have pursued scientific work.

Pauling believes that his wife, who died in 1981, enabled him to succeed in his field. "By handling all the family problems that might disrupt me, she saw to it that I could carry on my work," he says. According to his daughter, Linda Kamb, 60, "He tended to be pretty much lost in his work." He and Ava did love to dance, though, and Pauling often waltzed Linda around the living room.

From the 1920s to the '60s, Pauling taught chemistry at Cal Tech. It was Ava who encouraged him to venture into the public realm as well. In World War II the couple began traveling around the world, lecturing about the dangers of nuclear testing, and in 1946 Pauling helped form the Emergency Committee of Atomic Scientists, of which Einstein was the chairman. That great man, says Pauling, "was a lot of fun. My wife would tell him jokes about politicians, and he'd laugh uproariously." (Einstein, when asked about Pauling, once said, "Ah, there's true genius.")

In 1952, because he belonged to a scientific organization run by a French Communist, the U.S. government accused Pauling of being a Communist himself. He denied the charge, refused to identify supporters of his anti-atomic testing stance and had his passport revoked—then reinstated, with much official embarrassment, when he needed to go to Norway to accept a 1954 Nobel for his studies on molecular structure and the chemical bond within atoms. Several years later he wrote a best-selling book, No More War!—a plea to set up permanent international agreements to end nuclear testing—and in 1962 won the Nobel Peace Prize for his antiwar activities. In 1963, due in part to Pauling's efforts, the U.S. signed the limited test-ban treaty.

And since the publication of Vitamin C and the Common Cold in 1970, he has obstinately persisted in his research on the subject. To this day, he stirs 18 grams of vitamin C—"300 times the recommended daily allowance," he announces cheerfully—into his morning orange juice. For obstinacy, if you're Linus Pauling, will gel you everywhere. To make this point, he unfurls a poster inscribed with a quote from George Bernard Shaw. A gift from a fan, the poster clearly sums up his philosophy:

THE REASONABLE MAN ADAPTS HIMSELF TO THE WORLD, it reads. THE UNREASONABLE ONE PERSISTS IN TRYING TO ADAPT THE WORLD TO HIMSELF. THEREFORE, ALL PROGRESS DEPENDS UPON THE UNREASONABLE MAN.