River Styx

In Greek mythology, Styx (/stɪks/; Ancient Greek: Στύξ [stýkʰs]) is a deity and a river that forms the boundary between Earth and the Underworld (the domain often called Hades, which also is the name of its ruler). The rivers Styx, Phlegethon, Acheron, Lethe, and Cocytus all converge at the center of the underworld on a great marsh, which sometimes is also called the Styx. According to Herodotus, the river Styx originates near Feneos. Styx is also a goddess with prehistoric roots in Greek mythology as a daughter of Tethys, after whom the river is named and because of whom it had miraculous powers.

The deities of the Greek pantheon swore all their oaths upon the river Styx because, according to classical mythology, during the Titan war, Styx, the goddess of the river, sided with Zeus. After the war, Zeus declared that every oath must be sworn upon her.Zeus swore to give Semele whatever she wanted and was then obliged to follow through when he realized to his horror that her request would lead to her death. Helios similarly promised his son Phaëton whatever he desired, also resulting in the boy's death. Myths related to such early deities did not survive long enough to be included in historic records, but tantalizing references exist among those that have been discovered.

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