The commandment tells us to speak truthfully whenever it is appropriate for us to speak at all. Respect for truthfulness does not compel us to reveal our minds to everyone or on every occasion. The Ninth Commandment assumes, no doubt, a situation that calls on us to speak. It does not ask us to tell the people at the next table in a restaurant that their manners are repulsive. It does not obligate a nurse to contradict a physician a…