The engine of history

How a population/group feels about its future, its so-called social mood, and how that mood biases collective events of all types is the focus of this article. Through a variety of examples running from trends in clothing styles to the collapse of world powers, the paper argues that the social mood dramatically influences the types of events we can expect to see on all time scales. The argument is advanced that the financial market price movements serve as a good sociometer for measuring the social mood on all time scales. Additionally, we present arguments showing that there is virtually no feedback from events to mood; that is, the mood is endogeneous to the population and is not determined by any sort of outside forces. Finally, the paper concludes with a research program for turning the hypotheses advanced here into a full-fledged scientific theory of collective human behavior.