“It is smart to have a deep appreciation for economic and investing history. History helps us calibrate our expectations, study where people tend to go wrong, and offers a rough guide of what tends to work. But it is not, in any way, a map of the future. A trap many investors fall into is what I call “historians as prophets” fallacy: An overreliance on past data as a signal to future conditions in a field where innovation and change are the lifeblood of progress.”

这儿有两种比较对立的观点。一种说法是历史总是在重复上演，另一种是历史无法完全预测未来。我觉得第一种说法应该改一下，人类总是在重复同样的错误。我们既要从过去的经验中吸取经验教训，也要对现在和未来的情况有就事论事的观察，从而做出综合的判断。很多建立在过去的客观前提和假设的结论是无法直接应用在新的情景中的，最多有一些借鉴意义，但还是要因地制宜，而不是循规蹈矩。

“The correct lesson to learn from surprises is that the world is surprising. Not that we should use past surprises as a guide to future boundaries; that we should use past surprises as an admission that we have no idea what might happen next.”

承认极端的”黑天鹅“和异常事件、人物都是无法预测的。

“What this means, in effect, is that all historical data going back just a few decades about how startups are financed is out of date. What we know about investment cycles and startup failure rates is not a deep base of history to learn from, because the way companies are funded today is such a new historical paradigm.”

承接上面的观点，很多从数据中得出的经验和模式是基于过去的数据的。如果数据本身的模式就发生了变化，你还用过去的模型去预测未来，来注定是失败的。在数据科学领域有一句很著名的话: Gargage in Gargage out.

“But since economies evolve, recent history is often the best guide to the future, because it’s more likely to include important conditions that are relevant to the future.”

这段让我想起了最近看的一个机器学习的例子，把一些久远的数据从训练集中删除，反而提高了最终模型的准确度。对于个人来说太过久远的经验可能会起到反作用，学会忘记很重要。

“It comes from investor John Templeton’s view that “The four most dangerous words in investing are, ‘it’s different this time.’” Templeton, though, admitted that it is different at least 20% of the time. The world changes. Of course it does. And those changes are what matter most over time. Michael Batnick put it: “The twelve most dangerous words in investing are, ‘The four most dangerous words in investing are, ‘it’s different this time.’”

这段话蛮好玩的。其实也就是表达历史是不是在重演的问题。