This book is Eric Voegelin's best-known work, where he introduced his concepts of cosmological, anthropological, and soteriological symbolizations of truth in contradistinction to Gnosticism. The book traces the development of modernity and its paradoxical condition of an age that advances and declines at the same time. On the one hand, since the Renassiance and Reformation, there has been unprecedented level of war and destructiveness; on the other hand, there has been stupendous progress in science and technology that allows high levels of material comfort.
For Voegelin, the evolution of Gnosticism was a partial answer to explain this paradox. He defined Gnosticism as symbolic form that reflects a belief among its followers of their own superiority and insight into metaphyscial reality, such that they can achieve liberation from the world of human constraints. While early Gnosticism tended to be politically inactive, modern Gnosticism has been revolutionary and destructive in ideological mass movements like Nazism and Communism.
The alternative to Gnosticism was various forms of symbolizations of truth: cosmological, anthropological, and soteriological. Cosmological symbols portray a society's institutions as a reflection of nature; anthropological symbols reflect the discovery of the individual psyche and its relation to right order that is beyond nature; and soteriological symbols indicate the experience of humans who encounter divine revelation. Although he believed these symbols of truth have declined in the West as principles of ordering society, Voegelin nonetheless thought a possible reversal of the decline of modern civilization was possible in the recovery of Greek philosophy, Judaism, and Christianity.