As Odysseus returns home from his exploits in the Trojan War, Homer (in The Odyssey) tells of Odysseus' struggle to return to Ithaca—to his wife, son and home. In some cases, he is sidetracked by an adventure or even held captive—as is the case with Calypso who holds the hero under her spell. The gods are very much involved in Odysseus' life—for example, Athena is his advocate and patron goddess.
As Odysseus makes his way home from the war, he meets Circe. The goddess provides him with knowledge of how to pass three deadly impediments: Scylla, Charybdis and the Sirens. She also warns that he and his men must not harm Helios' cattle:
Then you will coast Thrinacia, the island
where Helios' cattle graze, fine herds, and flocks
of goodly sheep... (Book XII, 89-91)
Now give those kine a wide berth, keep your thoughts
intent upon your course for home... (101-102)
But if you raid the beeves, I see destruction
for ship and crew. (104-105)
Circe goes on to warn Odysseus that should the cattle be harmed, that it will be many years before he arrives home...
...alone and old, the one survivor, all companions lost. (107-102)
Odysseus and most of his men survive their encounters with the three dangers of which Circe had warned them. Odysseus tries to get his men to avoid Thrinacia...
I said to the men, ‘My men, I know you are hard pressed, but listen while I tell you the prophecy that Teiresias made me, and how carefully Aeaean Circe warned me to shun the island of the blessed sun-god, for it was here, she said, that our worst danger would lie. Head the ship, therefore, away from the island.’
...but they insist upon landing there. Even in the face of their captain's warnings, they feast on Helio's cattle. The god Helios threatens that he will stop the sun from shining if his anger is not appeased at this violation, so Zeus sends down thunderbolts that destroy all but Odysseus, just as Circe had warned.
With ships and crew lost, Odysseus "drifts to Ogygia," the island where Circe lives. She keeps him there for seven years.
Hence I was carried along for nine days till on the tenth night the gods stranded me on the Ogygian island, where dwells the great and powerful goddess Calypso. She took me in and was kind to me...
[Poseidon was furious because Odysseus had blinded and humiliated the sea god's son, Polyphemus (as told by Odysseus in Book IX), and so Zeus allowed Circe to bewitch and hold Odysseus for seven years. However, in Poseidon's absence—and in answer to Athena's plea—Zeus finally releases Odysseus, and Athena goes about preparing for his homecoming.]
Had Odysseus' men heeded his warning about the cattle, our hero may well have arrived home much sooner, rather than after the full twenty years it ultimately takes for him to reach the shores of Ithaca again.
The Language of Literature. Evanston: McDougal Littell, 2006.