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

The Greeks understood the mysterious power of the below things. They are the ones who gave us one of the most beautiful words in our language, the word enthusiasm.

The more I know, the more nearly is my faith that of the Breton peasant. Could I but know all I would have the faith of a Breton peasant woman.

These microscopic organisms form an entire world composed of species, families and varieties whose history, which has barely begun to be written, is already fertile in prospects and findings of the highest importance. The names of these organisms are very numerous and will have to be defined and in part discarded. The word microbe which has the advantage of being shorter and carrying a more general meaning, and of having been approved by my illustrious friend, M. Littré, the most competent linguist in France, is one we will adopt.

Wine is the most healthful and most hygienic of beverages.

The grandeur of the acts of men are measured by the inspiration from which they spring.

To bring one's self to believe in a truth that has just dawned upon one is the first step towards progress; to persuade others is the second.