Know how to Contradict. A chief means of finding things out–to embarrass others without being embarrassed. The true thumbscrew, it brings the passions into play. Tepid incredulity acts as an emetic on secrets. It is the key to a locked-up breast, and with great subtlety makes a double trial of both mind and will. A sly depreciation of another’s mysterious word scents out the profoundest secrets; some sweet bait brings them into the mouth till they fall from the tongue and are caught in the net of astute deceit. By reserving your attention the other becomes less attentive, and lets his thoughts appear while otherwise his heart were inscrutable. An affected doubt is the subtlest picklock that curiosity can use to find out what it wants to know. Also in learning it is a subtle plan of the pupil to contradict the master, who thereupon takes pains to explain the truth more thoroughly and with more force, so that a moderate contradiction produces complete instruction.