Three times in 300 years, the clocks of history have struck together.

History has many slow rhythms: debt, money, technology, generations, elites, world order. Most of the time those clocks disagree. Right now they don't.

I collected 52 cycle theories, graded each one by its evidence, and tested how often they turn together. Two eras stand alone: the age of revolutions and 1914–45. Of the 23 frameworks that date their next turn, 21 place it between 2020 and 2045.

The essays, the data and every test, including the ones that failed, are coming here.