Homer claims Oceanus and Tethys, pictured in the lower half of this mosaic, were responsible for the birth of the gods, but Hesiod's version of the origins is generally accepted (see Gypsy Girl).

At first, I thought this was just a nice bit of background noise to make Oceanus stand out, or perhaps a hint that Eurydice was returning in some form. Eventually, though, my Greek mythology brain ...