God of the sea, earthquakes, and horses. Brother of Jupiter and Pluto, ruler of all waters. Also associated with freshwater springs and patronage of horse racing.
Neptune rules waters in Roman religion, including the sea the poets borrowed from Greek Poseidon. Older Italian cult, though, ties him as closely to freshwater and to horses as to the open Mediterranean. The Neptunalia in July was a festival of midsummer drought, when Romans built leaf shelters and remembered the god who could give or withhold water.
Brother of Jupiter
In the imported genealogy he is brother to Jupiter and Dis, sharing the world after Saturn's fall. Roman art gives him the trident and the sea-chariot. Roman calendars also remember Consus and other horse-gods whose turf overlaps his, which is why chariot teams and the Campus watering places sit near his name.
Earth-shaker in Italy
Poets call him Earth-shaker when they are translating Greek epic. In Italy his anger is drought, flood, and the sudden failure of a spring. Sailors still prayed to him, especially once Rome became a naval power, but he never quite became only a sea-king.
Primary Sources
Historical texts and references
“Meantime imperial Neptune heard the sound of raging billows breaking on the ground. Displeas'd, and fearing for his wat'ry reign, he rear'd his awful head above the main, serene in majesty.”
Worship & Cult
How Neptune was venerated in ancient times
Sacred Temples
•Temple of Neptune in the Circus Flaminius
•Campus Martius cult of Neptune Equester, close to the later circus and to horse-racing ground
Festivals & Celebrations
Neptunalia (23 July)
Worship Practices
In the July heat Romans built leaf shelters (umbrae) and kept the Neptunalia as a thirsty outdoor feast. Neptune's Roman life is water, horses, and the fear of drought more than a Greek-style sea epic. State sacrifice used a bull.
