A proven fact though is that an “economic crisis” is also an “intellectual crisis” in the economists tribe. For almost a century economists didn’t manage to reach a consensus on the final cause and perfect answer to such economic troubles. Mainstreamers say there is neither bubble nor boom-bust cycles, just complex states of the economy, due to atypical evolutions in factor structure, such as new technologies, that the government cannot ever systematically control. The ones grounded in Keynes’ work oppose with “market psychology” and anti-cyclic policies that can calm the boom and fight the bust. Finally, a third set blames all these problems on the fundamental model on which modern banking systems work, with a fractional reserve and the back-up of a central bank. The later belong to the Austrian School of Economics, whose theoryof business cycle the author of this article is going to briefly apply to the subprime crisis, as well as to its further developments.