"Are you a song-writer?" asks the woman at the next table. "I'm an investment banker. I'm always looking for the next big thing. And I think you're it. I'll pay you $1000 now, and you'll pay me all the future profits your new hit makes!"

Wow! She'll spend money now to have a chance to make more money later. It's risky, but if you become a star, this deal could really pay for her. And you don't even have a tangible product - she's buying the future value of something you created.

Money can be nothing more than a promise when the system is stable and people can be confident that the promise will be kept.