Chelasque sequentis: Augustus Occupying Libra's Place in Georgics I. 32-35

David J. White

Baylor University

In the encomium of Augustus with which Vergil opens the Georgics, the poet offers Augustus a choice of regions as the province of his divinity:  the earth, sea, heavens, and Underworld.  When suggesting the third alternative, the heavens, the poet indicates that Augustus will take his place among the constellations of the Zodiac:

Anne novum tardis sidus te mensibus addas
Qua locus Erigonen inter Chelasque sequentis
Panditur (ipse tibi iam bracchia contrahit ardens
Scorpios et caeli iusta plus parte reliquit).   [Georgics I. 32-35]

The names that Vergil uses for the constellations in this passage clearly reflect his model, Aratus; in particular, the designation of the constellation we call "Libra" as the "Claws" (Chelae) of Scorpio, and the observation that Scorpio (with its Claws) thus occupies more than its share of the zodiacal circle, are typical of Aratus and of poetic astronomical nomenclature up to Vergil's time.  Roman poets, however, in the generation after Vergil were well aware of the designation of Libra as a constellation in its own right, although they continued to use the traditional name of the Claws alongside the new name of Libra.  Vergil, aware of the new identification of Libra, makes use of this knowledge to honor Augustus:  a new constellation occupies the place where the Claws of Scorpio used to be, and that constellation represents Augustus and his government. 

The name Libra appears to be purely Roman.  That name, in addition to being suggested by the shape of the constellation, possibly arose from the fact that the sun occupies this sign during the autumnal equinox.  An alternate Greek name for this constellation, Zugos ("Yoke"), is found beginning in the 1^st cent. B.C., but it never completely replaced Chelae and never caught on among Roman poets.  Vergil's preference for the old name Chelae instead of the new name Libra probably reflects his desire to adhere as closely as possible to his model Aratus rather than his ignorance of the new name.  In this passage from the Georgics, Vergil accepts the creation of a new constellation between Virgo (Erigone) and Scorpio (Scorpios) and uses that creation to illustrate the fact that the new order of Augustus is displacing the old.  His acceptance of the new constellation in poetry encouraged later Roman poets to do the same, and it became common in the generation of poets after Vergil.

The sun occupied the space of Libra at Augustus' birth on 23 September (Suetonius, Aug. 5) – the same zodiacal space that the moon occupied at the founding of Rome (Manilius IV. 773).  Suetonius, however, also wrote (Aug. 94. 12) that Augustus considered his natal sign to be Capricorn; according to G. P. Goold, this is due to the fact that the moon was in Capricorn at the time of his birth.  Manilius (II. 507-9) also stated that Capricorn was Augustus' natal star.  Capricorn, however, is a small constellation that does not quite occupy one-twelfth of the zodiacal circle (Manilius I. 271); thus it is not a suitable symbol for the Princeps.  Libra is much more fitting:  not only is it a new sign in the Zodiac, but it also has demonstrable connections with Augustus' birth, Rome's founding and, as the Balance, with the idea of justice.  By associating Augustus with the constellation Libra, Vergil placed himself within an astronomical and poetic tradition while at the same time turning an astronomical innovation into a poetic innovation in praise of the Princeps.