This year, I'm on the side of the Angels

If anyone is still looking to understand the causes of the credit crisis, perhaps in order to figure out whether or not the bailout plan1 is a good thing to support, the following, which I quote from a commenter at Justin Fox's Curious Capitalist blog, does a funny and clever job of explaining a large part of the crisis. What it leaves out is first, the massive amount of gambling banks and other institutions were doing on the solvency of other companies via credit default swaps, and, as that article alludes to, the massive loans the institutions took out to leverage their bets. This is why far more money is at stake than just the loss of value on mortgage backed securities which the explanation does cover. Second, it doesn't discuss the methods Steve used to sell Bob a mortgage Bob should have known he couldn't afford. If you're interested in that aspect, take a look here. Anyway, the explanation (including why I just started talking about people named Bob and Steve):
The simplest (and this is simplifying a lot) explanation:

Bob took out a mortgage for $1000 from Steve on which he agreed to pay back $2000 over the next 30 years. Steve split that $2000 into five packages of $400 and sold them to Jack for $300 each.* Jack has bough dozens of these little $400 packages. He combines 10 of them from 10 different people into a $4000 security that pays interest. Which he then sells to Jim for $3500.**

Jim says hey, I'm an institutional investor and I got a diversified security that pays steady returns over a 30 year term and is backed by real estate value. Yay me for safe investing! It's even rated AAA by the bond agencies.***

Unfortunately, Bob didn't get the big raise he was counting on at work. Now he can't afford the mortgage payment on his house. So he goes to Steve, his local banker, and asks for a renegotiation. Steve tells him that he can't because the loan has been split up among many buyers and sold several times and they're definitely not willing to renegotiate their fixed rate of return even if Bob can find them.

So Bob defaults on his mortgage, and Steve forecloses on Bob's house to recoup the loan. Unfortunately lots of houses are getting foreclosed and put on the market. Now Steve can't sell Bob's house for $1000. He can only sell it for $500.

Meanwhile, Jim hears about this on the news and realizes its happening all over the country. Jim realizes he has no idea how much, if any, of his securities are actually going to pay out. He tries to sell them to Ted the other institutional investor, but Ted is trying to sell his mortgage securities too.

No one is quite sure how much these securities are worth, but they definitely seem like they're worth less than what was paid for them, and the real estate backing them doesn't look so hot either. So everyone is trying to sell and no one is buying. The value just keeps dropping lower and lower, but still no buyers come.

Now Steve has some nice girl named Judy who wants to buy a house. And two fellows named Ben and Luke who want to start a business and go to college respectively. But Steve can't get any money from Jim or Jack because they're getting wiped out by the falling value of their securities.

Fortunately, Judy has an Uncle Sam who has a money printing machine and he wants to buy up a bunch of these securities so that their value will stabilize and people will start buying and selling them again. Then Steve can get the money to lend to Judy to buy her house, and Luke to go to college and Ben to start his business.

But Uncle Sam's wife, HoR, won't let Sam do it. HoR says that Jack and Jim are jerks who don't deserve to have any money because they don't work hard down at the tire plant like everyone else. And Bob is stupid for counting on that promotion so he shouldn't have taken out that loan in the first place. HoR forbids Sam from buying anything. So Judy doesn't get her house, Ben doesn't get his business, and Luke doesn't go to college. All because HoR wanted to get even with people for being jerks, even though really she just ended up punishing Judy and Ben and Luke who didn't do anything wrong at all.

Then there was a Great Depression and the Economy tanked and everyone lost their jobs. The end.

*Note that at this point, Steve has made a real and immediate profit of $500 and wants to lend out another mortgage right away.

**Jack has also make a $500 real and immediate profit on every "batch" of mortgage securities he sells. Jack wants to go buy more of these from Steve so he can keep buying and slicing and packaging them.

***Jim gets a bonus from his boss for doing so good and borrows money from Steve to buy a bigger house.

1. “Rescue plan,” which bill supporters now prefer due to negative connotations of
bailout is no less accurate than bailout plan, but changing the names of things due to how they poll is still somewhat dishonest.