Macro-history is the branch of historical scholarship that deals with long-term patterns and trends. Its opposite is micro-history, defined as in-depth research into singular events or eras. Whereas a micro-historian might study shifting gender roles in the United States during World War II, a macro-historian instead might argue for the inevitability of wars occurring at regular intervals over hundreds or even thousands of years. Some 20th-century scholars posit that societies experience recurring long-wave patterns. The most famous of these theories is early-20th-century Russian economist Nikolai Kondratieff’s theory that economic booms and busts occur at roughly 40-year intervals, driven by transformations in technology and industry. Economists refer to this “wave” of boom and bust as the Kondratieff wave, or K-wave. Political scientist William R. Thompson argued in a 2020 paper that the K-wave theory has been somewhat recklessly applied to a broad range of phenomena, including “generational shifts, investment spikes, stock market oscillations, or war impacts,” and he cautioned that “[t]he more elusive the core identity of K-waves, the easier it is to take the subject less than seriously” (Thompson, William R. “Clusters of Technological Change in Pioneering Economies.” Power Concentration in World Politics, 11 June 2020). Such models challenge linear-progress narratives by focusing on recurring social moods and institutional resets, but—as Thompson implies—their definitional broadness can render them vulnerable to charges of unseriousness.

In The Fourth Turning Is Here, Neil Howe interprets modern history through the lens of the “saeculum,” a cyclical model with classical roots in Etruscan and Roman culture, where it was a unit of time pegged to the longest a person could expect to live. Howe adapts this tradition, defining the saeculum as a cycle of four distinct eras, or turnings, paced by generational succession. The book argues that society’s mood shifts predictably as generational archetypes—Prophet, Nomad, Hero, and Artist—age through their life cycles. Each turning comes with its own mood: a First Turning “High” of institutional strength, a Second Turning “Awakening” of spiritual upheaval, a Third Turning “Unraveling” of “strengthening individualism and weakening institutions” (12), and a Fourth Turning “Crisis” of societal upheaval. The most recent saeculum, for instance, includes the post-1946 “American High,” the 1960s “Consciousness Revolution,” the “Culture Wars” Unraveling, and the current “Millennial Crisis.” By applying this framework across centuries of Anglo-American history, the book identifies repeating patterns while also accounting for anomalies like the shortened Civil War saeculum, relying on the fungible boundaries of the saeculum to absorb any inconsistencies in periodicity.