I realize this is a very general question, but is it fair to say that ancient coins are smaller than modern issues because the mining/refining/minting technology of the time was in its infancy? I imagine a citizen of the Roman Republic, for instance, would be aghast at the size of a Morgan Dollar - that much silver would amount to a small fortune. What would that citizen have been able to buy with a half-centenionalis, or antoninianus? A loaf of bread? A week's groceries? Are there any historical data that describe the buying power of various ancient coins?
There is some. We had a thread about it maybe 6 months ago in the ancient section if you want to look. Some of the "best" data we have is from Diocletian's price edicts. They were basically price freezes trying to control inflation. From that you can see relative values, but understand that price freezes never work, and to actually buy something probably cost you twice the "official" price.
It would be difficult to track the economy of the Roman Empire if the details were known, just as it is difficult to keep track of the economy of the USA over the last couple hundred years. Various times seem to have various values on coins. One general thing to keep in mind and it seems logical to me that gold is mostly for the very rich, highly paid and high ranking soldiers. Silver is for the middle class and a lot of soldiers. Bronze or base metal, mostly for the masses and poor people. And of course small change. A lot of coins have values attached to them as a modern convention. Here is what I understand about some Republican and early Imperial coinage. GOLD: Aureus - 25 Denarii SILVER: Denarius - 4 Sestertii BRONZE: Sestertius - 1/4 Denarius, 2 Dupondii Dupondius - 1/2 Sestertius As - 1/2 Dupondius Semis - 1/2 As Quadrans - 1/2 Semis During the late Roman period, denominations are not really known and so a system is used. AE is used for bronze. AE1 - 25+ millimeters AE2 - 21-25mm AE3 - 15-21mm AE4 - 15mm and smaller There are many more denominations. I don't really feel like explaining all of it right now. lol
John, here is a link showing the edict setting the max prices by Diocletian. Its a snapshot in time, but still very interesting. http://www.forumancientcoins.com/numiswiki/view.asp?key=Edict of Diocletian Edict on Prices
There is a good book on the subject: http://www.amazon.com/Coinage-Economy-Ancient-Society-History/dp/0801852919#reader_0801852919 It is neither cheap or easy to find in libraries but covers the evidence pretty well as long as you realize that the late Roman period was as long after the beginning of coinage as we are after William the Conqueror sailed for England so you can't expect things to be consistent across the whole time.
I cannot recommend this book enough. It is the only economic analysis of the Roman period that fully integrates numismatic evidence.
So let's say I do some grocery shopping in Rome somewhere around the year 300, and let's pretend that the price controls of Diocletian et al are in place. Here's what I buy and the cost in Denarii... 1 Modius wheat 100 1 Modius lentils 100 2 Sextarii aged wine 48 1 Sextarius olive oil 40 1 Italian pound of beef 8 1 Brace chickens 60 25 Oysters 25 Total: 381 denarii (round to 380) If I got all those supplies in one place, perhaps I would have paid with the following denominations: 3 Argenteus (worth 100 denarii apiece), 3 Nummus (worth 25 denarii apiece), and 1 Radiate (worth 5 denarii). It seems odd to me that there wasn't a denomination to bridge the gap between the Solidus and Argenteus in the Diocletian values.
