Arnold J. Toynbee on the big endogenous social cycle

From the Somervell abridgement of A Study of History:

In studying the growths of civilizations we found that they could be analysed into successions of performances of the drama of challenge-and-response and that the reason why one performance followed another was because each of the responses was not only successful in answering the particular challenge by which it had been evoked but was also instrumental in provoking a fresh challenge, which arose each time out of the new situation that the successful response had brought about.

... This repetitiveness or recurrency of challenge is likewise implied in the concept of disintegration, but in this case the responses fail. In consequence, instead of a series of challenges each different in character from a predecessor which has been successfully met and relegated to past history, we have the same challenge presented again and again.... When the outcome of each successive encounter is not victory but defeat, the unanswered challenge can never be disposed of, and is bound to present itself again and again until it either receives some tardy and imperfect answer or else brings about the destruction of the society which has shown itself inveterately incapable of responding to it effectively.