The White Bull
The story is based on the Greek mythological tale of Europa and the bull, where the white bull is the king of the Greek gods, Zeus, in disguise. Zeus, the sky and thunder god of the Olympic pantheon, often wore a disguise when romantically pursuing mortal women, so as to avoid the eye of his wife and sister, Hera.
Phthonus
In Greek mythology, Phthonus (, "Phthónos") was the personification of jealousy and envy, especially in matters of love. He was said to be the counterpart of Nemesis. However, his power influenced not only himself and mortals, but also the gods as well (most famously Hera). It was he that directed Hera's attention to Zeus' many affairs, including one of his most famous, that with the Theban princess Semele. He also put the thought into Hera's mind to trick Semele into convincing Zeus into showing Semele his full glory, which killed her.