Today marks the 19th installment in a series of articles by titled, Heroes of Progress. This bi-weekly column provides a short introduction to heroes who have made an extraordinary contribution to the wellbeing of humanity. You can find the 18th part of this series here.

Today’s Hero of Progress is Louis Pasteur, a 19th century French scientist, who is commonly dubbed the “father of microbiology.” Pasteur is renowned for developing the germ theory of disease, creating the process of pasteurization (which prevents the spoiling of many food products), and for changing the way that scientists create vaccines.

Louis Pasteur was born to a poor Catholic family in Jura, France, on December 27, 1822. In 1839, Pasteur enrolled at the Royal College of Besançon, the same city in which he had attended secondary school. Within a year, Pasteur had earned his Bachelor of Letters. In 1842, he graduated with a degree in science. A year later, he started studying at the École Normale Supérieure, a graduate school in Paris. In 1848, Pasteur was appointed professor of chemistry at the University of Strasbourg.

In Strasbourg, Pasteur met his wife Marie. The pair married in 1849 and had five children. However, only two of those children survived to adulthood, while the rest died of typhoid. It is said that the death of his three children motivated Pasteur to study infections and vaccinations.

In 1856, when he was the dean of the faculty of sciences at the University of Lille, Pasteur started to study fermentation to help a local wine manufacturer overcome the problem of alcohol souring.

Before Pasteur, people believed in a doctrine of “spontaneous generation,” which held that life spontaneously appeared from non-living matter. That faulty reasoning was used to explain why food spoiled and how infections developed.

To disprove the theory of spontaneous generation, Pasteur “exposed freshly boiled broth to air in vessels that contained a filter to stop all particles passing through to the growth medium, and even with no filter at all, with air being admitted via a long tortuous tube that would not pass dust particles. Nothing grew in the broths: therefore the living organisms, which grew in the broths that had not been heated, came from outside as spores on dust, rather than being generated within the broth.”

Furthermore, Pasteur found that heating of beverages to a temperature ranging from 140F to 212F (60°C-100°C) killed the bacteria in those liquids. His first successful test was completed on April 20, 1862, and the process he developed came to be known as pasteurization. Pasteur patented his discovery in 1865.

Pasteur then turned his attention to the development of vaccines. He and his colleagues injected chickens with cultured cholera microbes. After many experiments, the team discovered that if the birds were injected with live cholera microbes after they had already been injected with a weaker strain of cholera, the chickens would remain healthy.

Pasteur thus became the first scientist to use artificially weakened viruses as vaccines. Pasteur then went on to develop a vaccine for anthrax in 1881. In 1885, Pasteur successfully developed a rabies vaccine.

In 1888, Pasteur had received enough donations to open the Pasteur Institute – a private foundation dedicated to the study of biology, micro-organisms, diseases, and vaccines. He remained director of his institute until he died on September 28, 1895.

Pasteur became the Grand Officer of the Legion of Honor in 1878. He received dozens of honorary awards and today there are some 30 institutes, and several hospitals, schools and streets named after him. When he died, Pasteur was given a state funeral in the Cathedral of Notre Dame and his body was interred in a vault beneath his institute, where it still lays today.

The work of Louis Pasteur fundamentally changed the world we live in. The proof he provided for the existence of the germ theory of disease revolutionized the way we think about human health. Pasteurization enabled us to preserve beverages and canned foods far longer than was previously thought possible. And, finally, Pasteur revolutionized the development of vaccines.

Much of modern science rests on Pasteur’s work. Without him, it is likely that hundreds of millions, if not billions, of people would not be alive today. For that reason, Louis Pasteur is our 19th Hero of Progress.