真实的经济都有周期。17世纪以来的灾难性经济衰退发生的次数不仅越来越多,越来越频密,而且触发衰退的事件越来越多样,越来越偶然。它们可能是,单个经济体经济政策失调;个别金融机构经营不善;金融市场一次大额交易严重失误;标杆型巨型企业倒闭;楼市或股市崩盘;累积投机泡沫破裂;甚至天灾疫情等等。以至于,经济运行拐点的到来就像突发心脏病,无法提前被通知,拐折总会不 The real economy has cycles. The catastrophic economic recession since the 17th century not only occurred more and more frequently and more frequently, but the events that led to the recession were more and more diverse and more and more accidental. They may be the imbalances in the economic policies of individual economies; the poor management of individual financial institutions; the serious failure of a major transaction in the financial markets; the collapse of benchmarking giant enterprises; the collapse of the property market or the stock market; the accumulation of speculative bubbles; and even natural disasters. So that the turning point of economic operation is like a sudden heart attack and can not be notified in advance.