It is to silence.

Stone walls have one ear." "Two, sometimes, count," I suggested, laughing.
"Yes, I should have said one ears! Non, non! I forget this damnable tongue of yours! When I arrive to great interest, it is to talk faster than it is to think, and--" A shrug of the shoulders finished the sentence.
"Let us speak French hereafter, my dear count," I suggested.
"Mon Dieu, mon Dieu! It is to me more of pain to hear my sweet language murdered than to murder yours," answered Grammont, seriously.
"Ah, but I speak French quite as well as I speak English.

Perhaps I shall not murder it," I replied.
"Perhaps?
We shall try," he said, though with little show of faith.
I began speaking French, but when I paused for his verdict, he shrugged his shoulders, saying:-- "Ah, _oui, oui!_ It may be better than my English." But notwithstanding his scant praise, we spoke the French language thereafter.
The count bowed himself out and left me to decipher, if I could, the problem of M.l'Abbe du Boise.

Presently I discovered the cue.

The Abbe was George Hamilton, and for the moment my heart almost stopped beating.