One good thing leads to another. That is, a situation in which improvement in one element of a chain of circumstances leads to improvement in another element, which then leads to further improvement in the original element, and so on.
Although U.S. bankers were cautious until late last year, owing to concern over rising delinquency rates and deteriorating household balance sheets, recent indicators suggest that they have again become aggressive lenders. And thanks to the booming economy and the tight labor market, even delinquency rates have been falling in 1997, making bankers even more optimistic.
All this suggests that a "virtuous cycle" is starting, in which confident bankers finance more investment projects, which in turn creates jobs and income, which in turn boosts asset prices, which in turn makes bankers even more confident.
Richard C. Koo, "Is U.S. seeing start of 'bubble' trouble?," Los Angeles Times, August 10, 1997
In Europe, where the fluctuations of the dollar have produced strong criticism of U.S. policies, a concept is evolving to describe the kinds of actions many bankers think governments should take especially the U.S. government to stabilize currencies. They call it the "virtuous cycle," one in which a series of sound economic policies sets off a chain of events in which improved economic performance produces sound currencies. This in turn helps to improve economic performance further.
"Europe's new byword: The 'virtuous cycle'," Business Week, February 12, 1979
This phrase is a play on vicious cycle. A similar phrase virtuous circle has been in the language since at least 1953.