Two-horse chariots are a common icon on Roman coins; see bigatus, a type of denarius so called because it depicted a biga.
[10] A yoke of two horses is associated with the Indo-European concept of the Heavenly Twins, one of whom is mortal, represented among the Greeks by Castor and Pollux, the Dioscuri, who were known for horsemanship.
[11] Horse- and chariot-races were part of the ludi, sacred games held during Roman religious festivals, from Archaic times.
[13] The sacral meaning of the races, though diminished over time,[14] was preserved by iconography in the Circus Maximus, Rome's main racetrack.
Inscriptions referring to the bigarius as young[15] suggest that a racing driver had to gain experience with a two-horse team before graduating to a quadriga.
[16] A main source for the construction of racing bigae is a number of bronze figurines found throughout the Roman Empire, a particularly detailed example of which is held by the British Museum.
In the Mithraeum of S. Maria Capua Vetere, a wall painting that uniquely focuses on Luna alone shows one of the horses of the team as light in color, with the other a dark brown.
It has been suggested that the duality of the horses drawing a biga can also represent Plato's metaphor of the charioteer who must control a soul divided by genesis and apogenesis.
[25] Triptolemus is depicted on Roman coins as driving a serpent-drawn biga as he sows grain in response to Demeter's appeal to him to teach mankind the skill of agriculture, such as on an Alexandrine drachma.