Louis Pasteur was born in Dole, France on December 27, 1822. He grew up in the town of Arbois, where his father worked at a leather tannery.

In 1847, Louis earned his doctorate in physics and chemistry at the Ecole in Paris. He was given a research position under one of his teachers, where he found that a beam of polarized light rotated when it passed through natural organic nutrients. This allowed him to hypothesize that organic molecules exist in isomer forms, where they have the same shape, but are occasionally mirror images of each other.

He continued his research and began lecturing as well at universities in Dijon and Strasbourg. In 1854, he moved to Lille, where he was given a position as the dean of science at the local university. He immediately began working on research in the processes of fermentation for the local wineries, demonstrating that alcohol production depended on the quantity of yeast. He also discovered that the sour taste present in wine was a result of bacterial contamination of the wine.

Soured wine was a huge problem in France's wine industry, costing the businesses huge amounts of money. Pasteur began looking for ways to remove the bacteria and other organisms from the wine without compromising the quality. Eventually, he discovered that by heating the wine, the bacteria was killed and couldn't produce the acids that soured the wine. Pasteur applied this same process to the problem of souring milk, by heating the milk to a high temperature before it was bottled. His process was named pasteurization and made him famous throughout the world, revolutionizing several industries.

Now that Pasteur saw that microorganisms were indeed the cause of contamination in wine, he began to think about how they were introduced into the wine in the first place. Another leading scientist at the time, Felix Pouchet, believed that the organisms were generated spontaneously in the wine and could not be prevented from appearing. Pasteur challenged this idea, stating instead that the bacteria was introduced via the air and other mediums.

In 1865, Pasteur was asked to help solve a problem with the French silk industry. A massive epidemic had seized upon the silkworm population, in the form of pebrine. He eventually discovered through controlled breeding that the disease was hereditary and could be contagious. His methods of controlled egg selection saved the silk industry in France from impending doom.

By now, Pasteur was beginning to get the idea that at least some diseases were caused by microscopic organisms that could spread through the air and water. He developed what is known as germ theory, whereby tiny germs infect larger organisms and cause symptoms of disease. This theory was hotly debated, but as more and more proof was produced it soon became obvious that he was right.

Pasteur was the first scientist to produce a vaccination for anthrax, a disease that mainly affected cattle. He believed that anthrax was caused by a bacillus and that animals could be given an injection of weakened anthrax, which would allow their immune systems to develop a natural immunity to the disease. He tested his theory on a number of sheep, and it proved his theory, allowing farmers to protect their animals from a terrible affliction.

After his success in anthrax, Pasteur began researching cures for other diseases. He became fascinated by the disease known as rabies, where animals were driven to become very hostile and foam at the mouth. He found that the disease was one of the nervous system and that extracts from the spinal column of afflicted animals could be injected into other animals to spread the disease. He used this technique to develop a weakened form of the rabies virus, which could be used for vaccination.

His first test of his new vaccine was on a young boy in 1885. The boy had been bitten by a rabid dog and was brought by his mother to Pasteur's laboratory. Pasteur administered a very strong inoculation, which caused the boy to recover to normal health. His discovery led to the creation of the Institut Pasteur, where Pasteur served as director of research until his death on Septermber 28, 1895.