To demonstrate experimentally that a microscopic organism actually is the cause of a disease and the agent of contagion, I know no other way, in the present state of Science, than to subject the microbe (the new and happy term introduced by M. Sédillot) to the method of cultivation out of the body.
Louis PasteurWithout theory, practice is but routine born of habit. Theory alone can bring forth and develop the spirit of inventions.
Louis PasteurThe controls of life are structured as forms and nuclear arrangements, in a relation with the motions of the universe.
Louis PasteurScience advances through tentative answers to a series of more and more subtle questions which reach deeper and deeper into the essence of natural phenomena.
Louis Pasteur