In 1918 a vicious strain of flu spread to every populated continent, snuffing out lives faster than coffin makers could supply caskets. The Spanish flu killed as many as 50 million people over two years. People who were perfectly healthy when they woke up in the morning could be dead by nightfall. Medical classes were canceled so that students could serve as doctors and nurses. In Europe, military strategists on all sides of World War I scrambled to redraw battle plans for lack of healthy soldiers.

Surrounded by death and reduced to simply comforting patients with aspirin, a desperate doctor in Pittsburgh asked a nurse whether she knew a better way to save lives. The nurse, who had worked with homeopaths, urged the skeptical doctor to switch to their simple remedies, which she had seen save countless lives.

According to the late homeopathic historian and authority Julian Winston, a victim of the Spanish flu treated by a conventional doctor had only a 70 percent chance of surviving; homeopaths saved 99 percent of their patients. Now a number of modern-day homeopaths believe they can help fight another pandemic -- a rare bit of hopeful news given that, as this magazine went to press, neither the mainstream medical establishment nor the pharmaceutical industry had found a way to counter H5N1, the virus that causes avian flu.

German physician Samuel Hahnemann discovered homeopathy 200 years ago when he found that cinchona bark containing quinine, then the best treatment for malaria, caused all the symptoms of malaria in a healthy person. After experimenting with more than 200 substances, he concluded that like cures like. Give someone with a runny nose a homeopathic solution of onion, that pungent veggie that normally causes a runny nose, and it strengthens the body in just the right way to heal. If you're suffering from insomnia, a homeopath will give you a controlled dose of a caffeine-like substance.

Homeopaths dilute substances in double-distilled water, vigorously shake the mixture, and then dilute it again, explains homeopath Dana Ullman. They repeat this over and over until it's unlikely that a single molecule of the original substance remains, and then deliver what's left in a pill. No one knows exactly why this works, but homeopaths posit that water retains the energy of a substance and delivers a message to the body. (Ullman likens it to rubbing a magnet on a piece of metal to transfer the magnetic properties.)

Because of its success in treating the era's epidemics, homeopathy enjoyed its greatest popularity during the 19th century. Just before the American Medical Association was founded as an alternative to the American Institute of Homeopathy, there were 22 homeopathic medical schools in the United States, including at Boston University and Stanford. Today, the method is most popular in England, where 40 percent of conventional doctors refer patients to homeopaths.