“Do you think that to be an agriculturist it is necessary to have tilled the earth or fattened fowls oneself? It is necessary rather to know the composition of the substances in question⁠—the geological strata, the atmospheric actions, the quality of the soil, the minerals, the waters, the density of the different bodies, their capillarity, and whatnot. And one must be master of all the principles of hygiene in order to direct, criticize the construction of buildings, the feeding of animals, the diet of domestics. And, moreover, Madame Lefrançois, one must know botany, be able to distinguish between plants, you understand, which are the wholesome and those that are deleterious, which are unproductive and which nutritive, if it is well to pull them up here and re-sow them there, to propagate some, destroy others; in brief, one must keep pace with science by means of pamphlets and public papers, be always on the alert to find out improvements.”

The landlady never took her eyes off the Café Français and the chemist went on⁠—