These were covered very nicely in a speech some years ago by Hans van Wijk, former chair of the Irving Fisher Committee.1 Fisher worked on monetary theory, and on understanding the determinants of the rate of interest, saving and investment. The distinction between the nominal and real rate of interest – second nature to economists today – was first made by Fisher.
In the 1980s, the credit cycle was in an expansion mode with a few exceptions, and the 1990s were a period of adjustment followed by expansion again in the 2000s. Because of the global financial crisis following the Lehman shock in 2008, the expansion of private-sector debt has come to an end, and we are now in an adjustment phase on a global basis.