As (Roman Coin)

The as (plural asses) was a bronze, later copper, coin of the Roman Republic and Empire. It began in the early third century BCE as a heavy cast disc of bronze that nominally weighed one Roman pound, and over the following two centuries it shrank into a small struck coin. For most of Roman history it was the basic unit of small change against which larger silver and gold pieces were reckoned.

The as gave its name to a whole family of bronze fractions and stayed in production, in changing forms, for roughly five centuries. It faded out during the monetary upheavals of the third century CE, when rising prices and a collapsing silver coinage left little room for low-value bronze.

Before Rome struck coins, central Italy used weighed lumps of raw bronze, known as aes rude, and later cast bars, as a means of payment. The first true asses, part of the series called aes grave ("heavy bronze"), were cast in moulds from around the 280s BCE. They were linked to the Roman pound of twelve unciae and are often called "libral" for that reason, although surviving pieces vary considerably in weight.

Rome was influenced by its neighbours. Cast bronze was already used in parts of central Italy, including some cities covered under Etruscan coinage, while the Greek cities of southern Italy had long struck silver on standards derived from the Attic drachma and its relatives. Roman bronze bridged the two traditions.

The weight of the as fell repeatedly, a long-run case of currency debasement driven largely by the cost of war. Modern numismatists describe a sequence of standards, from semilibral (half a pound) through triental and quadrantal to sextantal (one-sixth of a pound). The sextantal as is associated with the introduction of the silver denarius during the Second Punic War, around 211 BCE, when Rome also began striking its bronze rather than casting it.

The new system tied the metals together. The denarius was originally worth ten asses, hence its name, and the small silver sestertius two and a half. In the second century BCE the denarius was retariffed at sixteen asses, and this ratio lasted into the imperial period. The as became chiefly a unit of account as much as a physical coin: prices, fines and military pay could be stated in asses even when few were being minted. Later reductions brought the coin to an uncial (one-twelfth pound) and then a semuncial standard by the early first century BCE.

Production of Roman bronze was irregular in the late Republic. Under Augustus the base-metal coinage was reorganised: the sestertius and dupondius were struck in orichalcum, a golden-coloured brass, while the as was struck in reddish, almost pure copper. Its value stayed at a quarter of a sestertius and one-sixteenth of a denarius, beneath the gold aureus at the top of the system.

Imperial asses usually carried the emperor's portrait and a reverse type, often with the letters SC (senatus consulto), and they served as everyday money in markets, baths and taverns across the western provinces.

The standard Republican as showed the two-faced god Janus on the obverse and the prow of a ship on the reverse, together with the value mark I. Its fractions had their own deities and marks of value given in pellets: the semis (half), triens (third), quadrans (quarter), sextans (sixth) and uncia (twelfth). This duodecimal system influenced Roman weights and measures as well as money.

From the reign of Nero onwards the silver content of the denarius was gradually lowered, and in the third century CE the silver coinage collapsed into the base antoninianus. The resulting inflation made a coin worth one-sixteenth of a denarius almost useless. Asses became scarce by the middle of the century, and the monetary reforms of Aurelian in the 270s and Diocletian in the 290s replaced the old bronze denominations with new ones. Gresham's law also played a part, as older heavier coins were withdrawn from circulation or melted.

The as survives in Latin usage, for example aes alienum ("another's bronze") meaning debt, and the Greek form assarion appears in the New Testament as the name of a small coin. Its history is a standard example of how a currency that began as a valuable weight of metal turned into small change whose worth rested mainly on the authority of the state, a step in the long origins of fiat money.

• British Museum
• American Numismatic Society