*  *  *  Our day-by-day experiences with the effectiveness of flexible markets as they adjust to, and correct, imbalances can readily lead us to the mistaken conclusion that once markets are purged of rigidities, macroeconomic disturbances will become a historical relic. However, the penchant of humans for quirky, often irrational behavior gets in the way of this conclusion.
A discontinuity in valuation judgments, often the cause or consequence of the building and bursting of a bubble, can occasionally destabilize even the most liquid and flexible of markets. I do not have much to add on this issue except to reiterate our need to better understand it.