One of the earliest examples of the motif comes from the Ancient Greek tale of Perseus, who rescued the princess Andromeda from Cetus, a sea monster often described as resembling a serpent or dragon. This was taken up into other Greek myths, such as Heracles, who rescued the princess Hesione of Troy from a similar sea monster. Most ancient versions depicted the dragon as the expression of a god's wrath: in Andromeda's case, because her mother Cassiopeia had compared her beauty to that of the sea nymphs, and in Hesione's, because her father had reneged on a bargain with Poseidon. This is less common in fairy tales and other, later versions, where the dragon is frequently acting out of malice.