Rome was, to use a modern term, on the gold standard.  The gold, in this case, was their coinage. It worked for a while but, as they say, the longer there is a government, the more it costs. As the United States would discover in 1933, the gold standard is, well, not what it’s cracked up to be.  In 1933, the United States ditched the gold standard.  The Romans tried something different. When the Empire went into the red, again, to use a modern term, molten bits of lead were slipped into the gold coins. It worked for a while, but when Roman businesses learned of the inserted lead, they raised prices. Which caused inflation. So the Roman treasury added more lead and, and, so the value of the coins dropped and prices went up.