Cognitive dissonance is a motivating state of affairs. Just as hunger impels a person to eat, so does dissonance impel a person to change his opinions or his behavior. The world, however, is much more effectively arranged for hunger reduction than it is for dissonance reduction. It is almost always possible to find something to eat. It is not always easy to reduce dissonance. Sometimes it may be very difficult or even impossible to change behavior or opinions that are involved in dissonant relations. Consequently there are circumstances in which appreciable dissonance may persist for long periods.