My friend Gus disagrees with me on this subject. Facebook Have you seen a post from a Facebook friend asking you to participate in a book exchange? The system is basically an old-school fraudulent chain letter. It won't work the way you probably expect, and it might be illegal.

Here's the text from a typical post:

Hello all! Calling out to all of you who are bookworms, book lovers, and bibliophiles (like myself) from all walks of life. We need at least 6 people to participate in a book exchange (but can be more). You can be anywhere in the world. The further we get, the better! All you have to do is buy one of your favorite books and send it to one person. You will receive approximately 36 books back! If you are interested like this status so I can fill you in on all the details!

Sounds harmless, right?

Here's the problem.

Chains like this — with every new member sending books or gifts or money backward to the last people on the chain— are basically efficient systems for enriching a small group of people at the expense of a much larger group. In fact, no matter how big the chain grows, it's mathematically impossible for more people to get free stuff than people who spend money without getting anything at all.

The chain asks you to believe that if you send an item to one person you stand to benefit because you will recruit six more people and they'll all send you books. Of course, once you finish those books you send them along to the person who recruited you. And all the books your recruits receive will eventually end up in your hands.

But because each link on the chain has to include more people than the last one for the chain to work, there will always be this massive, expanding group of people who have bought books and sent them up the chain that far outweighs the group of people who have received books. Eventually, the chain will run out of steam with a small group of people at the middle who've managed to hoard lots of books and a giant group of people who eagerly signed up but ultimately spent money they'll never get back.

Even if the chain spread all over the world, it would eventually die out when all seven billion people had signed up, and it would die with billions more losers than winners. You are much more likely to be one of the losers.

The only difference between this book chain and chain letters that typically target elderly, under-educated, or otherwise vulnerable people is that it seems to go after college-educated nerds.

In case you don't care, maybe because you're confident you're jumping on board early enough that you think you're guaranteed to be one of the winners, you should know that there's a good chance it's illegal.

The U.S. Postal Service says this on the matter:

They're [chain letters] illegal if they request money or other items of value and promise a substantial return to the participants. Chain letters are a form of gambling, and sending them through the mail (or delivering them in person or by computer, but mailing money to participate) violates Title 18, United States Code, Section 1302, the Postal Lottery Statute. (Chain letters that ask for items of minor value, like picture postcards or recipes, may be mailed, since such items are not things of value within the meaning of the law.)

Recently, high-tech chain letters have begun surfacing. They may be disseminated over the Internet, or may require the copying and mailing of computer disks rather than paper. Regardless of what technology is used to advance the scheme, if the mail is used at any step along the way, it is still illegal.

The main thing to remember is that a chain letter is simply a bad investment. You certainly won't get rich. You will receive little or no money. The few dollars you may get will probably not be as much as you spend making and mailing copies of the chain letter.

The only halfway sensible argument in favor of participating in one of these schemes that I've seen came from my friend Gus Schlanbusch, who wrote on Facebook, "It's fundamentally a pyramid scheme, only instead of investing money for potentially no return you're giving someone a book for potentially no return and I do that sometimes anyway."

In other words, only participate if you're comfortable with the overwhelming likelihood that you're sending a book to someone but will receive nothing in return. I'd add that you have a moral obligation to make that abundantly clear to your recruits as well.

That said, you shouldn't participate in fraudulent, exploitative, possibly illegal chain mail schemes.

If you're looking for free books, I have great news for you. There's almost certainly a place near your home where thousands are available for free. It's called a public library.