This epigraph provides a one-line summary of the theme of this book. The conductor introduces causality, the orchestra diversity, and the violins universality. Causality, diversity, and universality are complex phenomena producing complex problems, certainly with regard to an already complex topic such as the origins of culture. To put the problems as simply as possible, it is easy to challenge climato-economic causation of culture, it is difficult to chart cultural diversity in an indisputable way, and it is impossible to demonstrate statistically the existence of universal needs arising from survival of cold and heat. Some explanatory remarks on each of these complications follow, first for climato-economic causality.

The central tenet of my theory is that climate and cash influence each other's impact on culture. A lot of evidence seems to support this idea. But factors other than climate and cash may also cause the results. Seasonal cycles and day-night cycles, for instance, may be responsible in whole or in part for the simultaneous occurrence of (a) harsh climate, poverty, and survival culture in Azerbaijan, Russia, and elsewhere; (b) temperate climate and easygoing culture in Ghana, Singapore, and elsewhere; and (c) harsh climate, affluence, and self-expression culture in Austria, the United States, and elsewhere. Certainly, rival explanations in terms of precipitation, income inequality, inflation rate, former communist rule, and the like have been ruled out.