AFTER the grim economic developments of the last few weeks, it’s easy to lose hope. Could the Great Recession of 2008 drag on for years, just as the Great Depression did in the 1930s? Adding to the despair is the oft-repeated notion that it took World War II to end the economic nightmare of the ’30s: If a global war was needed to return the economy to full employment then, what is going to save us today?

Look more closely at history and you’ll see that the truth is much more complicated — and less gloomy. While the war helped the recovery from the Depression, the economy was improving long before military spending increased. More fundamentally, the wrenching wartime experience provides a message of hope for our troubled economy today: we have the tools to deal with our problems, if only policy makers will use them.

As I showed in an academic paper years ago, the war first affected the economy through monetary developments. Starting in the mid-1930s, Hitler’s aggression caused capital flight from Europe. People wanted to invest somewhere safer — particularly in the United States. Under the gold standard of that time, the flight to safety caused large gold flows to America. The Treasury Department under President Franklin D. Roosevelt used that inflow to increase the money supply.

The result was an aggressive monetary expansion that effectively ended deflation. Real borrowing costs decreased and interest-sensitive spending rose rapidly. The economy responded strongly. From 1933 to 1937, real gross domestic product grew at an annual rate of almost 10 percent, and unemployment fell from 25 percent to 14. To put that in perspective, G.D.P. growth has averaged just 2.5 percent in the current recovery, and unemployment has barely budged.