I believe that this is a fundamental question as to the nature of coins in commerce in the Roman Republic. Were the coins taken at “face value” or were they valued by their intrinsic worth? Also, with constant new designs entering circulation virtually every year, how did the consumer & merchant cope with what seems like a very confusing situation?
Face value.
This is very well proven
(a) by thousands of documents that mention prices in
denarii and
asses. It's clear from the context of
shopping lists and letters that an as was an as and a
denarius was a
denarius.
(b) purse
hoards or
shop tills that show small change of all eras circulating
side by
side in a context that presumes a large
triens and a small
triens were exactly the same (or else they would have been sorted). For example the tills in Pompeii mix heavy and light coins together without distinction, and the prices are advertised in
asses and their fractions. This only makes sense if everything was accepted at
face value.
(c) savings
hoards which show the heavy and light coins mixed without distinction. There are occasional savings
hoards where the hoarder endeavoured to choose heavier or unworn coins but that's an exception and is anyway no different to how one would choose the crisper bank notes to put in a savings box today.
This is a 100% established fact for all of the
Roman Republic. It is not debated or disputed at. One of the drivers for this was that the
standard for the
denarius remained absolutely unchanged from the second Punic war to
Nero - over 250 years. So despite the legionaries being a tiny
bit light they entered circulation in an era when a
denarius was just a
denarius.
But probably a more important driver was the willingness of the government tax collectors to accept the same coin in tax payments or for
buying the corn-dole. If they were accepted at
face value then there was really no point in sorting out the heavy from the light.
During the
Imperatorial era, as the empire was split up for nearly two decades, the relationship between prices and coins in the provinces seem to have shifted, witness for example the halving of
asses in
Gaul, the tiny size of the Fleet coinage etc. But not, so far as I am aware in
Rome. After the bronze recoinage of 19 BC onwards and the old bronzes were removed in time, the new ones would have circulated at their new
face values. And a
denarius remained a
denarius as ever.