Louis Pasteur

Louis Pasteur revolutionized medicine and biology by definitively disproving spontaneous generation and establishing the germ theory of disease. His experiments demonstrated that microorganisms cause fermentation and spoilage, leading to the process of pasteurization. Most importantly, he proved that germs were the cause, not the consequence, of disease. This foundational insight led Joseph Lister to develop antiseptic surgery, saving countless lives.

Pasteur himself developed vaccines for rabies and anthrax, creating the field of immunology. His work transformed medicine from a practice based on tradition and humorism to one based on identifiable causes and preventative science, laying the groundwork for modern epidemiology, public health, and the pharmaceutical industry.