Time is the best appraiser of scientific work, and I am aware that an industrial discovery rarely produces all its fruit in the hands of its first inventor.

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.

Do not put forward anything that you cannot prove by experimentation.

The more I study nature, the more I stand amazed at the work of the Creator. Science brings men nearer to God.

Science belongs to no one country.

Worship the spirit of criticism. If reduced to itself it is not an awakener of ideas or a stimulant to great things, but, without it, everything is fallible; it always has the last word.

Inspiration is the impact of a fact on a well-prepared mind