Odysseus looks for his way back home from the Trojan War. Circe, the daughter of Apollo, advises the hero to find the soothsayer Tiresias to get the directions from her. However, Homer sends Odysseus to the underworld for the epic to show us his heroic journey.
Detailed answer:
The Odyssey was written by an ancient Greek poet Homer. In the 24 books, he shows us the heroic adventure of the protagonist – Odysseus. All the characters are based on Greek mythology and put the reader into the Olympic Gods world.
So, the story follows: Odysseus loses his direction to Ithaca. Circe, the daughter of Apollo, advises him to find Tiresias, the oracle. She tells him to sail to the edge of the world – to Oceanus. When he arrives, he has to sacrifice rams and let their blood fill a ram attracting the Hades spirits. The soothsayer gives Odysseus specific details on his life. It turns out that he expands our knowledge of his future journey: filling in Sirens or Scylla gaps, for instance. Nevertheless, she doesn’t let him know how to avoid death from Poseidon, though Circe could give this information.
But it isn’t the end of the story. Odysseus’ travel to the underworld and his reemergence is an incredibly heroic achievement. In other words, the event increases Odysseus’ glory. As if a victory of the Cyclops wasn’t enough. By now, you could get that the actual cause of Odysseus’ travel doesn’t matter.