Not surprisingly, the figure in the middle of the fountain is Neptune, the god of the sea. Neptune's chariot is drawn by two winged horses, with two Tritons (representing calm and stormy seas, respectively) guiding his progress. Allegories of Abundance and Health can be found in the two niches on either side of the burly mermen, while the Four Seasons calmly survey the madness from on high, just under the Corsini family arms. In good old Roman style, the fountain's source is an aqueduct - specifically the Acqua Vergine aqueduct, which also supplies the spouts in P. Navona and P. di Spagna. The relief at the top of the fountain on the left shows the fountain's namesake, Trivia, the maiden who allegedly pointed out the spring for the aqueduct to thirsty Roman soldiers. The opposite relief shows Augustus's right-hand man, Agrippa, giving the go-ahead for the aqueduct in 19 BC.