Pales was the shepherd's deity of early Latium, the god (or goddess — the gender was variable in different sources) of flocks and pastures. The festival of Pales, the Parilia, fell on April 21, which was traditionally the day of the founding of Rome itself — and so Pales's festival became the Roman state's birthday celebration. The rites were rural and ancient: shepherds bathed their sheep at dawn, garlanded the sheepfolds with branches, sprinkled the ground with water, made a smudge-fire of straw and rosemary that the sheep were driven through (a ritual purification of the flock for the new pastoral year), and offered cakes of millet and bowls of milk to Pales. Then the shepherds themselves leapt three times through the smudge-fire, in a gesture of personal purification; the festival concluded with feasting in the open air.
The translation of this rural festival to the urban context of Rome's birthday gave it a doubled character: it was both the shepherd's spring rite and the city's annual recommitment to its founding. The rites were observed without major modification through the entire Roman period; the practical agricultural purposes of the original festival continued to operate alongside the political-symbolic function of the Roma birthday. Pales was variously imagined as one deity or as twins (the masculine and feminine Pales together) or as a triad; the tradition was unsettled and the deity may originally have been a numen rather than a personalized god.

