pushing on a string
n.— «The attempt to pump money into the banking system failed, and as a result, the phrase “pushing on a string” was coined to describe the futility of inflationary policies in this environment.» —“Wisdom from Richard Russell on the Inflation/Deflation Topic” by Jay Taylor HoweStreet.com Nov. 21, 2005. (source: Double-Tongued Dictionary)
Further reading
If you speak a second or third language, you may remember the first time you dreamed in that new tongue. But does this milestone mean you’re actually fluent? And a couple’s dispute over the word regret: Say you wish you’d been able...