Some lessons applicable to the current crisis in the United States can be found by examining the period leading up to the Great Depression.

From the NYT's Dave Leonhardt:

In 1929, Meyer Mishkin owned a shop in New York that sold silk shirts to workingmen. When the stock market crashed that October, he turned to his son, then a student at City College, and offered a version of this sentiment: It serves those rich scoundrels right.

A year later, as Wall Street’s problems were starting to spill into the broader economy, Mr. Mishkin’s store went out of business. He no longer had enough customers. His son had to go to work to support the family, and Mr. Mishkin never held a steady job again.

Frederic Mishkin — Meyer’s grandson and, until he stepped down a month ago, an ally of Ben Bernanke’s on the Federal Reserve Board — told me this story the other day, and its moral is obvious enough. Many people in Washington fear that the country is starting to spiral into a terrible downturn. And to their horror, they see the public, and many members of Congress, turning into modern-day Meyer Mishkins, more interested in punishing Wall Street than saving the economy.

All of which may be true. But there is good reason for the public’s skepticism. The experts and policy makers who so desperately want to take action have failed to tell a compelling story about why they’re so afraid.

It’s not enough to say that markets could freeze up, loans could become impossible to get and the economy could slide into its worst downturn since the Great Depression. For now, the crisis has had little effect on most Americans, beyond their 401(k) statements. So to them, the specter of a depression can sound alarmist, and the $700 billion bill that Congress voted down this week can seem like a bailout for rich scoundrels.

Mr. Bernanke and his fellow worriers need to connect the dots. They need to use their bully pulpits to teach a little lesson on the economics of a credit crisis — how A can lead to B, B to C and C to Depression.

Let’s give it a shot, then.

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Why are we talking about the Depression, anyway?

Almost no economist thinks that even a terrible downturn would look like the Depression. The government has already responded more aggressively than it did in Herbert Hoover’s day. So a Depression-like contraction — a 30 percent drop in economic activity — is highly unlikely. The country is also far richer today, which means that a much smaller portion of the population is living on the edge of despair. No matter what happens, you’re not likely to see shantytowns.

But the Depression is still relevant, because the basic mechanics of how the economy might fall into a severe recession look quite similar to those that caused the Depression. In both cases, a credit crisis is at the center of the story. ...

The crucial point is that a modern economy can’t function when people can’t easily get credit. It takes a while for this to become obvious, since most companies and households don’t take out big new loans every day. But it will eventually become obvious, and painfully so. Already, a lack of car loans has caused vehicle sales to fall further.

Could the current crisis lift — could banks decide they really are missing out on profitable investing opportunities — without a $700 billion government fund to relieve Wall Street of its scariest holdings? Sure. And is Congress right to fight for a workable program that’s as inexpensive and as tough on Wall Street as possible? Absolutely.

But in the end, this really isn’t about Wall Street. It’s about reducing the risk that something really bad happens. It’s about limiting the damage from the past decade’s financial excesses. Unfortunately, there is no way to accomplish that without also extending a helping hand to Wall Street. That is where our credit markets are, and we need them to start working again.

“We are facing a major national crisis,” as Meyer Mishkin’s grandson says. “To do nothing right now is to do what was done during the Great Depression.”