 His introduction and conclusion suggest that an objectivist natural history approach to human history, in which subjective factors are of local importance but fade out in terms of lasting effects over generations, is a valid approach to the "pre-Axial" condition of human societies, while a subjectivist history of consciousness is a necessary complement to the "post-Axial" condition.Korotayev succeeds in placing these two complementary approaches in context and showing their linkages in terms of how subjective and religious factors play out in human history alongside objective factors such as demography and ecology, each informing the other.He shows how it is impossible to arrive at valid inferential results from comparative approaches without an integration of the two, a situation he aptly calls "Galton's opportunity" for those are of century-old critiques of the comparative method.