In Greek mythology, Zeus decided to seduce Europa, and so transformed himself into a white bull and mixed in with her father’s herds. When Europa saw him she went over and gave him a pat. Seeing how tame and agreeable the bull was, Europa hopped on top for ride, but the bull took off running for the sea and swam all the way to the island of Crete, raped her, and then made her queen of the island. Zeus later created the shape of the bull in the stars in her honour and called the constellation Taurus.
Pierre gives us the moment when the bull swims across the sea; an underwater sea creature is propelling them along. Mermen and the Nereids frolic in the sea, while putti dance in the sky. We also see an eagle there, the eagle being a personification of Zeus.