Explanations & Theories
Genealogy: The Muse Calliope, Orpheus' mother, was one of the most famous and eloquent of muses. Apollo, among other things, was god of the lyre and poetry. Ironically, Apollo was also the son of a nymph. Orpheus was the grandson of Jupiter, which is probably why his lyre was placed there after his death.
Orpheus' death: There are many different ways the story of Orpheus and Eurydice is told. Some tell of Orpheus dying because, after Eurydice's "second death", he sang so sadly, and "held himself aloof from womankind", that some Thracian maidens threw stones and javelin at him and he died. Thomas Bulfinch's version says, "The muses gathered up the fragments of his body and buried them at Libertha, where the nightingale is said to sing over his grave more sweetly than in any other part of Greece". Some say that he committed suicide.
The Serpent: In the story of Orpheus and Eurydice, a serpent bites Eurydice's foot. Either the serpent was poisonous, or it was a large one, because it seems like a small thing to kill Eurydice so quickly. One definition of a python, a kind of serpent, is "A soothsaying spirit or demon; a person possessed by such a spirit". This serpent could have been a symbol for Aristaeus' attack on Eurydice when she was picking the flowers. So it could have meant anything, not only an actual bite on her foot by a serpent. Also, it could be coincidence, but it was said that Apollo (Orpheus' father) had killed a serpent at Delphi. So it seems the serpent is a symbol often used in Greek mythology.
Versions: With some versions of this story, the story simply stops after Orpheus comes out of the underworld empty-handed, while others continue to tell of how he dies and, according to Thomas Bulfinch's Orpheus and Eurydice, "his shade passed a second time into Tartarus, where he sought out his Eurydice and embraced her with eager arms".
Themes: There could be many reasons and/or themes of this story, why it was written. It could be a subject of time. If Orpheus had held back for a few moments, he might have lived a long life with Eurydice. In the end, Orpheus spends eternity with Eurydice. It could also be death, and love. Eurydice dies, and Orpheus goes to the place where death is, Eurydice dies again, and then Orpheus dies, and they end up together anyway.
The Furies: The thing that is so spectacular about the Furies weeping at Orpheus' song is that they were considered extremely stern. The Furies were the spirits who punished wrongdoers. As in Bulfinch's version of the story, "Then for the first time, it is said, the cheeks of the Furies were wet with tears".
The power of Orpheus' song: Obviously, if Orpheus' music calmed a three-headed dog, then it was very powerful. It's been said that the effect of Orpheus' song was to lead man to love. This is why even Hades and Persephone were in tears. In Thomas Bulfinch's story, it tells of how, after Orpheus arrives from the underworld without Eurydice, the Thracian maidens throw things at him. At first they don't hit him, because he was playing his lyre. "The weapon, as soon as it came within the sound of his lyre, fell harmless at his feet….But the women raised a scream and downed the voice of the music, and then the missiles reached him and soon were stained with blood." As the story heightens, so does Orpheus' maturity. In many different versions, it tells of how he first searches the Heavens and "planets" for Eurydice, before he goes to the Underworld. Orpheus didn't inherit all of his musical talents. It was said that on his journey, he learned much about music that allowed him to be able to bring the gods and others in the underworld to tears.