The economist John Maynard Keynes argued that market behavior could not be rational, or subject to improvement, since our existing knowledge did not provide a sufficient basis for a calculated mathematical expectation of investment returns. I think this observation is particularly true when the object of speculation involves the application of a new technology, such as the Internet.
Modern financial theory attempts to surmount the problem of an unknowable future by suggesting that returns can be predicted by measuring the past volatility of share prices -- shares that exhibit higher volatility are expected to yield greater returns. Yet this assumes the future will be a continuation of the past -- like steering a car by looking in the rear-view mirror. Investors therefore remain heavily dependent on their emotions. The feelings of "greed" and "fear” , that drive markets remain constant throughout the ages.
经济学家约翰·梅纳德·凯恩斯曾经说过，市场的行为不可能是理性的，也不可能改进，因为我们现有的知识不能为经过精确计算而得出的投资收益预期提供充分的依据。我认为在投机对象涉及到新技术的使用时，例如因特网的使用，凯恩斯的这种看法尤为正确。
现代金融理论试图解决未来不可预测的问题。按照现代金融理论，投资收益可以通过对股价以往的波动幅度来预测，也就是说，股价波动较大的股票可望带来较大的回报。但是这种理论是以未来是过去的延续为前提的，如同看着后视镜驾驶汽车一样。所以投资者仍然在 很大程度上凭着自己的情感操作。在任何年代，推动市场的“贪心”和“担心”这两种心情 总是永恒不变的。
