In Louis Pasteur's scientific career it is striking to note the exponential character of the research he introduced in all the fields he opened up. He offered fabulous opportunities to stereochemistry. He is acknowledged as one of the founders of microbiology. He established the possibility of anaerobic life. He pointed the way to epidemiology, public health, and the bacteriologic fight. He struggled against the idea of spontaneous generation of life. He irrevocably substantiated the microbial theory of infectious diseases. He demonstrated that bacterial virulence could be attenuated, he evidenced immunity and generalised the vaccination principle. He also was an incomparable experimenter.