… is from page 254 of Jennifer Burns’s 2023 Milton Friedman: The Last Conservative (link added):
Friedman and [Anna] Schwartz’s data [from 1929-1933] showed a precipitous 33 percent decline in the quantity of money during what they called “the great contraction.” They convincingly argued that this lack of money transformed an unremarkable dip in the business cycle into a crisis of global proportions. Here was a provocative new explanation for a disaster that continued to cast its shadow across the century. But threaded through the economic argument was another thesis. In 1914, the United States had created a central bank system designed expressly to stabilize the economy. As lender of last resort, the Federal Reserve Board could have opened the spigots and flooded the economy with cash. Why did it fail to do so?