Doug Casey: Let's look at the definition of what makes a good money. There are basically six characteristics. A good money has to be durable, divisible, convenient, consistent, have use value, and some limit on supply. Using those six key characteristics, gold ranks first, silver second, and copper third. That's why those three metals have been preferred money throughout history. They were superior to seashells, salt, cows, paper, and other commodities. In today's world it makes sense to bring Bitcoin, which also satisfies those six characteristics into the mix.

So, to answer the question: Silver has always been a monetary metal, and it likely always will be.

International Man: Do you think gold functions better as money than silver—and if so, why? If not, why not?

Doug Casey: Gold is much scarcer than silver. It has an extremely high unit value. And its value relative to silver has increased throughout history. In the days of Ancient Egypt, gold traded at only three times the value of silver. In Rome, at the time of Caesar, the gold aureus was worth about 12 times more than the silver denarius. The US initially fixed the value of gold against silver at 17.5 to 1. Incidentally, fixing the value of any commodities—which fluctuate widely for many reasons—is always a bad idea. As of now, the ratio is about 100 to 1. The increase in gold's value relative to silver is a trend that, with fits and starts, has been in motion for over 3,000 years.