"According to the academic world view that markets are efficient, only the revelation of a dramatic piece of information can cause a crash, yet in reality even the most thorough post-mortem analyses are typically inconclusive as to what this piece of information might have been. For traders and investors, the fear of a crash is a perpetual source of stress, and the onset of the event itself always ruins the lives of some of them."

“Perhaps the most profound synthesis of physical sciences came from the realization that everything could be understood from "conservation laws" and symmetry principals.”

“Profiting from being in the minority leads to interesting paradoxes. Rather diabolically, if all traders use the same set of rules, they will end up doing the same thing at the same time and cannot therefore be in the minority.”

“By one estimate, 90% of international transactions were accounted for by trade before 1970, and only 10% by capital flows. Today, despite a vast increase in global trade, that ratio has been reversed, with 90% of transactions accounted for by financial flows not directly related to trade in goods and services.”

“Positive feedbacks, when unchecked, can produce runaways until the deviation from equilibrium is so large that other effects can be abruptly triggered and lead to ruptures and crashes.”

“A bubble that goes up is just one that could have crashed but did not.”

“Knowledge is encoded in models. Models are synthetic sets of rules, and pictures, and algorithms providing us with useful representations of the world of our perceptions and of their patterns.”