"Not in theory, monsieur, only in practice."

"Well, then, you will know enough to understand my illustration."

"I am listening, monsieur."

"Monsieur Dumas, in order that a machine may work properly, none of its wheels must stop."

"Of course not, monsieur."

"Very well, Monsieur Dumas; I need not say more. I am the engineer, you are one of the wheels in the machine; for two days you have stopped, and consequently for two days the general action of the machine has lacked the co-operation of your individual movement."

I rose to my feet.

"Quite so, monsieur," I said.

"You will understand," added M. Lefèvre in a less dogmatic tone, "that this warning is merely provisional?"

"You are very good, monsieur, but I take it as definitive."