This picture is the result of Strauss and Howe’s intriguing interpretation of American history. The authors find a clear pattern after looking back 500 years: Each cycle in modern history lasts roughly as long as a full human life and is made up of four eras, or “turnings,” that each last roughly twenty years and always occur in the same order. The authors of The Fourth Turning brilliantly analyse the post-World War II era to show these cycles.