Barton, T. S., 1994, Power and Knowledge: Astrology, Medicine and Physiognomies under the Roman Empire, 40-1.
Astrology was firmly constructed as a legitimator with Augustus’s establishment of the principate. The Iulium sidus belonged to the realm of traditional omens, but the princeps’s publication of his birth sign on coins to be seen all over the empire accorded astrology a new, superior status. Suetonius says that Augustus made his horoscope (thema) public and issued a silver coin with Capricorn, his birth sign, on it. He attributes Octavian’s confidence to a consultation with the astrologer Theogenes in 44 b.c. and sets the publication of the horoscope some unspecified time soon afterward. As Libra was Augustus’ Sun sign, there has long been some debate about the role of Capricorn: both signs are given prominence by the poets. Bouchd-Leclerq and others argue that it was the “chronocrator” of the month of conception (the sign designated as presiding over that month), despite Suetonius’ specification that it was his birth sign. Meanwhile, Riess (1896) and others argue that, as the sign in which the Moon was at the hour of the birth, it was the determining “birth sign.” Gundel (1926) argues that it was the sign in which Augustus’s “Lot of Fortune” was to be found as well as where the Moon was, which would help explain the cases in which Capricorn is to be found portrayed with the attributes of Fortune and Manilius’ use offelix of Capricorn.
Whatever Capricorn’s precise relation to Augustus’s birth, it is probably significant that it was seen as the birth sign of the Sun, in that the winter solstice takes place in Capricorn. According to Suetonius, he was bom just before the sun rose. As Dwyer (1976) points out, a clever astrologer could have suggested to the young Octavian that Capricorn was an auspicious sign for this reason. Given the associations the princeps cultivated with the sun and Apollo in the early years, it fits well Dwyer himself suggests that, on the basis of Nigidius Figulus’ commentary on the sign of Capricorn, it is to be associated with Pan and his role in restoring the rule of the gods, saving the world from the tyranny of the Titans. He goes further and suggests that, before Actium, the theme of the righteous revenge of the son is implied by the myth narrated by Nigidius. Thus, Capricorn may have first of all symbolized Octavian’s just revenge on the killers of his adoptive father, Julius Caesar, and, only after Actium, liberation from tyranny. Capricorn is also associated with rule over the West in the poets. Dwyer connects Capricorn’s rule over the West with Aeneas’ westward journey. In addition to all this speculation, it is worth noting that Augustus’s principate was inaugurated under Capricorn.
Kraft (1967), who provides photographs of several examples, argues that the appearance of Capricorn on coins from at least 41 /40 B.C. onward is to be linked in another way with Octavian’s careful self-presentation. He claims that the sign was used first of all against Mark Antony. The first surviving coin with the sign of Capricorn may have been minted by Q. Oppius, the praefectus classis (prefect of the fleet) based at Cyrene in 41/40, a partisan of Octavian, who set Capricorn by the head of the Venus of the Julian family, sometimes with the half-moon.Glass pastes and cameos with Capricorn on them, mainly Italian, were also produced before Actium. Examples show Capricorn with a bearded Octavian; or a young Octavian’s head over a ring (Caesar’s signet ring, pointing to his heirship), with Capricorn, com ears and a poppy; or with a child riding on its back over the waves, identified as Octavian and dated to the 40s. Hölscher even identifies one depiction of Capricorn on a glass paste as dating from the period of reconciliation with Antony, as Octavian’s head is placed above the intertwined signs of Capricorn and Leo, Antony’s conception sign. But the sign only played a small role in the public presentation of Octavian before Actium. The first appearance of Capricorn on Augustus’s own coins in 28 B.C. was on the obverse of a denarius (silver coin) from the Eastern mint, together with Augustus’s head, with the crocodile of Egypt and the legend Aegypto capta (Egypt taken), referring to the victory over Antony. Aurei (gold coins) and denarii of the same type followed, while from 27-20 b.c. tetradrachms (coins worth three denarii) from Asia showed Capricorn with a cornucopia on its back.
Barton, T. S., 1994, Power and Knowledge: Astrology, Medicine and Physiognomies under the Roman Empire. Ann Arbor: The University of Michigan Press.