Kenneth, the wonder of modern banking (not really modern as it goes back several hundred years) is that bankers worked out that people did not come back to get their gold and silver all at once.
When this was realised and smart people did the numbers they realised they could actually lend most of it out. When they got even smarter and people accepted a bit of paper with pictures on it as legal tender... they realised they could just keep handing the stuff out.
Real interesting story of how the monetary system came about and lots of books to read that are very interesting.
