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.

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.

Bernard was right. The germ is nothing, the terrain is everything.

Whatever your career may be, do not let yourselves become tainted by a deprecating and barren scepticism.

The only thing that can bring joy is work.

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.

Never will the doctrine of spontaneous generation recover from the mortal blow struck by this simple experiment.