4. The Dioscuri on Roman coins
The Dioscuri first appeared on Republican coins in 225 BC and were used frequently down to 46 BC. Apart from the coins minted at Ostia by Maxentius, images of the Dioscuri were rarely used during the Empire, although they do make a final appearance on the 500 lire coins minted from 1951 to 2001 AD where they can be seen in front of the Quirinal Palace.
The Dioscuri were extremely important gods for the Romans, far more so than they had been to the ancient Greeks. They represented the ever-changing cycle from dark to light and light to dark, but were also honoured as Gods of the athletes. Castor was renowned as a breaker of horses and Pollux was a master boxer. To the soldiers, and particularly the cavalry, they were the supreme models of courage and bravery. The Dioscuri were known to be special protectors of sailors and could calm the seas and still the winds, thus protecting during storms. They were especially honoured in Rome because of their appearance at Lake Regillus helping the Romans to victory against the Latins in c. 496 BC. The Games of Castor and Pollux were held on January 27th, probably taking the form of horse racing, and this tradition continued well into the Imperial period. A large temple was built in the Roman Forum to commemorate events at Lake Regillus and the Temple of Castor and Pollux in Ostia has recently been identified by Michael Heinzelmann and Archer Martin in the area west of the Imperial Palace. An inscription tells of its restoration in the 2nd century AD by P. Lucilius Gamala and another record describes it as being situated on the "right side of the river". Bearing all this in mind, together with the desire of Maxentius to return to the classical times, it is not surprising that the Dioscuri feature on the coins produced at the Ostia mint.
In Republican Rome, anyone with aspirations to high political status had to negotiate the cursus honorum. This meant working from the lowest of public offices up to the pinnacle, consulship. The office of moneyer was low in the hierarchy but was often used as a stepping stone to a career in the Senate. Moneyers generally held office from their early twenties but it is not known if they were appointed or elected. In all probability they would have been selected from a pool of candidates from the equestrian order.
It is thought that there were three moneyers during each term of office, but only one of them in any given year could 'sign' the coinage IIIVIR (Triumviri Monetales). Not all coins were signed as such, but almost all from 148 BC carried the name of the moneyer or a monogram of his name. It was against the customs of Rome to use portraits of living Romans on the coinage. ROMA appeared frequently on the obverse faces of coins throughout the Republic and at times, so did the Dioscuri on either the obverse or the reverse face.
The first silver coins to be produced in significant quantities were the didrachms of 225 to 212 BC. The janiculate heads of the Dioscuri appear on the obverse with Jupiter riding in a quadriga on the reverse. Conjoined heads of the twins also appear on later issues. In 211 BC the first denarii were produced with ROMA on the obverse and the Dioscuri on horseback, a star above their heads, on the reverse. The Dioscuri continued to be used on these coins for sixty years.
The silver quinarii of 187 to 175 BC show ROMA on the obverse and the twins on horseback, carrying spears, on the reverse. On the silver sestertii of 187 to 155 BC, they are shown on horseback galloping to the right.
From 148 BC, the Dioscuri appear with the name or monogram of the moneyer added, i.e. Q. Marcius Libo (148 BC), M. Junius Silanus (145 BC), C. Servilius (136 BC), Cn. Lucretius Trio (135 BC), M. Atilius Saranus (123 BC), Q. Minucius Rufus (122 BC), C. Fonteius (114 to 113 BC), C. Font (108 to 107 BC) and Manius Cordius Rufus (46 BC). On the coinage bearing the name Manius Cordius Rufus (46 BC), Venus Verticordia appears on the reverse with conjoined heads of the Dioscuri on the obverse. The Cordia family came from Tusculum where there was a strong Dioscuri cult.
Apart from the coins minted at Ostia and the appearance of Castor alone on a coin of Geta, there is only one more reference to the Dioscuri on Imperial coinage. Bronze coins were minted in 360 to 363 AD during the reign of Julian II that show a bull on the reverse with two stars above, possibly representing the twins. If this is in fact the case, it is the last time that pagan images were used on Roman coinage.