The Templars offered security to travelers on the road to the Crusades. They held the wealth of travelers by military might, and issued paper IOUs to be traded back in for wealth on demand. All the Templars asked for in return was a portion of your lands in trust, while you were away, to use to produce food at a profit. But it was observed that people traded the IOUs rather than the wealth itself. Gradually, more IOUs than wealth that was held were printed. The Central Bank paradigm, and modern monetary theory was born.