REMEMBER: The dollar was originally measured in GOLD, not the system we have today in which gold is measured in DOLLARS!
We live in such an artificial system that normal people don't even know what dollars are. Like every other unit of measurement, a "dollar" was originally a unit of measurement defining a set weight of gold. This was when we were on the gold standard.
Even before that, dollars didn't exist! Everything was measured by the free market and in weights, such as grains or grams.