“At different times in our history a varying set of simple indicators seemed successfully to summarize the state of monetary policy and its relationship to the economy. Thus, during the decades of the 1970s and 1980s, trends in money supply, first M1, then M2, were useful guides.”

“Unfortunately, money supply trends veered off path several years ago as a useful summary of the overall economy.”

Greenspan, 1996

https://www.federalreserve.gov/boarddocs/speeches/1996/19961205.htm