When Harel wished to put a joke or witticism into circulation, he was in the habit of connecting it with some celebrated name, on the chance of reclaiming it if it took. Thus he assigned to Talleyrand, in the "Nain Jaune," the phrase, "Speech was given to man to disguise his thoughts."
"Hoyt's New Cyclopedia Of Practical Quotations" by Jehiel Keeler Hoyt, p. 740-45, L'Esprit dans l'Histoire, 1922.