The Strauss and Howe 'generational cycles' idea, a framework about repeating historical patterns.
It claims history runs in long cycles of about 80 years, with four recurring generational types.
The cycle runs through four moods — Prophet, Nomad, Hero, Artist — and the crisis stage of the current cycle is said to have begun in 2008.
It offers a lens for reading present-day upheaval as a predictable phase rather than random chaos.