Post by steffenkd

In other words: I am not sure if the authors just used data which fit their thesis or if there really is something to that 80-100 cycle and the four archetypes. It is mainly for USA over the last 400-500 years and there maybe/probably is some tweaking.

However, there definitely are "ups and downs over time in all aspect of life", even mountains becoming valleys and mountains again.
And since this concept is much more fundamental than that 80-100 cycle thesis from the book I think a short summary of the book is good enough for everybody who stumbled over the initial concept already.