Rolf Nef of Global Research, wrote in "Falling Empires and their Currencies" (1/5/07, GlobalResearch.ca):
"When empires fall, their currencies fall first. Even clearer is the rising debt of empires in decline, because in most cases their physical expansion is financed with debt ...
The common thing is that the currencies of each and every one of these falling empires lost dramatically in value ...
... The Roman Empire existed from 400 B.C. to 400 A.D. Its history is the history of physical expansion, like the history of almost all empires.
Its expansion was driven by a citizen soldier army, paid in silver coins, land and slaves from occupied territories.
If there was not enough silver in the treasury to conduct a war, base metals were added to coin more money.
... That is to say, the authorities debased their currency which presaged the fall of the Empire. There was a limit to the expansion.
The empire became over-stretched, running out of silver money, and eventually went under, overrun by barbarian hordes."