Then all the rigor, hard work, and hard thinking that had made Linus Pauling a legend disappeared. In the words of a colleague, his "fall was as great as any classic tragedy."

The turning point came in March 1966, when Pauling was 65 years old. He had just received the Carl Neuberg Medal. "During a talk in New York City," recalled Pauling, "I mentioned how much pleasure I took in reading about the discoveries made by scientists in their various investigations of the nature of the world, and stated that I hoped I could live another twenty-five years in order to continue to have this pleasure. On my return to California I received a letter from a biochemist, Irwin Stone, who had been at the talk. He wrote that if I followed his recommendation of taking 3,000 milligrams of vitamin C, I would live not only 25 years longer, but probably more." Stone, who referred to himself as Dr. Stone, had spent two years studying chemistry in college. Later, he received an honorary degree from the Los Angeles College of Chiropractic and a "PhD" from Donsbach University, a non-accredited correspondence school in Southern California.

Pauling followed Stone's advice. "I began to feel livelier and healthier," he said. "In particular, the severe colds I had suffered several times a year all my life no longer occurred. After a few years, I increased my intake of vitamin C to ten times, then twenty times, and then three hundred times the RDA: now 18,000 milligrams per day."

From that day forward, people would remember Linus Pauling for one thing: vitamin C.

In 1970, Pauling published Vitamin C and the Common Cold, urging the public to take 3,000 milligrams of vitamin C every day (about 50 times the recommended daily allowance). Pauling believed that the common cold would soon be a historical footnote. "It will take decades to eradicate the common cold completely," he wrote, "but it can, I believe, be controlled entirely in the United States and some other countries within a few years. I look forward to witnessing this step toward a better world." Pauling's book became an instant best seller. Paperback versions were printed in 1971 and 1973, and an expanded edition titled Vitamin C, the Common Cold and the Flu, published three years later, promised to ward off a predicted swine flu pandemic. Sales of vitamin C doubled, tripled, and quadrupled. Drugstores couldn't keep up with demand. By the mid-1970s, 50 million Americans were following Pauling's advice. Vitamin manufacturers called it "the Linus Pauling effect."

Scientists weren't as enthusiastic. On December 14, 1942, about thirty years before Pauling published his first book, Donald Cowan, Harold Diehl, and Abe Baker, from the University of Minnesota, published a paper in the Journal of the American Medical Association titled "Vitamins for the Prevention of Colds." The authors concluded, "Under the conditions of this controlled study, in which 980 colds were treated . . . there is no indication that vitamin C alone, an antihistamine alone, or vitamin C plus an antihistamine have any important effect on the duration or severity of infections of the upper respiratory tract."