extraordinarythis is the thing that is supposed to drive the...

extraordinary

this is the thing that is supposed to drive the trade cycle

Credit cycle
The credit cycle is the expansion and contraction of access to credit over the course of the business cycle. Some economists, including Hyman Minsky and members of the Austrian school, regard credit cycles as the fundamental process driving the business cycle.
It works a bit like this-
During the upward phase in the credit cycle, asset prices experience bouts of competitive, leveraged bidding, inducing asset price inflation in a particular asset market due to the recursive "ballooning" nature inherent in fractional reserve banking. This can then cause an unsustainable, speculative price "bubble" to develop. As this upswing in new debt creation also increases the money supply and stimulates economic activity, it tends to temporarily raise economic growth and employment.
When new borrowers cannot be found to purchase at inflated prices, a price collapse can occur in the market segment inflated by excess debt, along with a dramatic reduction in liquidity in that market. This can then cause insolvency, bankruptcy, and foreclosure for those borrowers who came in late to that market. If widespread, this can then damage the solvency and profitability of the private banking system itself, resulting in a dramatic reduction in new lending as lenders attempt to protect their balance sheets from further losses. This in turn results in a contraction in the growth of the money supply, often referred to as a "credit squeeze" or a "drying up of liquidity".
Prime examples of this "boom-bust" cycle of credit creation and destruction can be found in the United States housing bubble and the subsequent subprime mortgage crisis, the dot-com bubble and the Japanese asset price bubble.