The artificial products do not have any molecular dissymmetry; and I could not indicate the existence of a more profound separation between the products born under the influence of life and all the others.

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

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.

When I approach a child, he inspires in me two sentiments; tenderness for what he is, and respect for what he may become.

You have not succeeded in your experiments, that is all there is to it.

The greatest derangement of the mind is to believe in something because one wishes it to be so.

I am on the edge of mysteries and the veil is getting thinner and thinner.