In the tradition of the orthodox Marxists, Mandel tried to characterize the nature of the modern epoch as a whole, with reference to the main laws of motion of capitalism specified by Marx. Mandel's aim was to explain the unexpected revival of capitalism after World War II, contrary to leftist prognostications, and the long economic boom which showed the fastest economic growth ever seen in human history. His work has produced a new interest in the theory of long waves in economic development.