Picture of Louis Pasteur Courtesy of The Bettmann Archive. From painting by Edelfeld.

Louis Pasteur was a French chemist who lived between 1822-1895. He discovered that fermentation, the process used to make beer and wine, is carried out by tiny animals. Pasteur called these microorganisms "germs", and learned that they are also responsible for spreading contagious diseases. He thus solved the mystery behind rabies, and created vaccines for this and other deadly illnesses, saving many lives.

Pasteur also dispelled the myth of spontaneous generation, proving that all life comes from pre-existing life.