The 74 stone statues along the two polygonal basins were sculpted by Nicola Pisano and Giovanni Pisano, They were great 13^th century artists who, together with Arnolfo di Cambio, regained skills that could be likened to the ancient Greek and Latin sculptors.
The panels on the lowest basin are low reliefs that show episodes from the Bible, allegories, the months of the year with their respective human activities, and the Liberal Arts. The statues on the central basin are high reliefs showing both historical and mythological personages, as well as allegoric figures.
But, both sculptural sets should be examined by the aid of some mental keys. The lower cycle, creating a sequence, can be better understood by going round the fountain anticlockwise starting from the first pair, the episode of the original sin in the Bible. As a matter of fact, it often happens to see people or groups making “a round around the fountain” to watch its statues. It proves however harder to grasp the meaning and beauty of the statues on the middle basin, set higher and therefore farther from our eyes. They are placed in an order that can hardly be guessed if you had no preliminary notion. This cycle is structured like a compass rose, the four statues in the direction of the cardinal points being the most important, and the meaning of the other twenty being in strict relationship with them. Unlike the “water carriers,” all the statues on the two polygonal basins display small inscriptions, carved in the stone, which indicate their subjects, making them easier to be understood – by scholars at least.