From Lenin's Seer: I Warned You.

NIKOLAI KONDRATIEFF was not exactly a faceless bureaucrat in post-revolutionary Russia. He had held an important economic post in the last, short-lived government of Alexander Kerensky before the Bolsheviks took charge; then he founded an influential research organization, the Institute of Conjecture, and became an important theorist of the New Economic Policy under Lenin. But he would long ago have been consigned to the dustbin of history had it not been for his quirky academic passion, which he pursued in a series of books and papers through the 1920s. Reviewing economic history since the late 18th century, Kondratieff came to a startling, doomsday conclusion: that capitalist economies were fated to go through regular and predictable cycles of around 50 years, inevitably culminating in a depression. [ABSTRACT FROM PUBLISHER]