to hold me firm, upright against the mast-block,—round it let the rope be wound."

In other words, Circe has told Odysseus precisely what to do in order to hear the sirens singing, and, perhaps, it would feel like a missed opportunity to him if he passes up the chance without taking it. He says that she only told him what to do, and this seems to affirm her speech about the fact that no one has ever heard the sirens before and lived to tell the tale of it. She told him,

"Whoso draws near unwarned and hears the Sirens' voices, by him no wife nor little child shall ever stand, glad at his coming home; for the Sirens cast a spell of penetrating song, sitting within a meadow."

The idea that Odysseus could do something that no one else has ever done is likely very appealing to him. He is a proud man—as we see when he tells Polyphemus his real name so that he can take credit for blinding the Cyclops—and sometimes his pride outstrips his caution when he sees an opportunity to gratify his vanity (like in the example with the Cyclops). Why take the risk of hearing the sirens at all? He has nothing to gain by it, nothing except being able to tell the story later (as he is doing now). Thus, it seems as though he wants to hear them singing because it would make him proud to be the only person who can tell the story of what they sing.

Odysseus wants to hear the Sirens' sweet, seductive song because he's confident that if he follows Circe’s advice—blocking his men’s ears with wax and having them lash him to the ship’s mast—he will be the only man to have experienced the joy of listening to the Sirens and lived to tell about it. So, it's partly out of curiosity, partly out of pride, and partly because he can get away with it.

All other sailors who had sailed past the Sirens' island had become mesmerized by the song, forgetting about their homes and dying of hunger:

. . . whoever comes their way . . .

. . . and listens to the Sirens

singing, has no prospect of coming home. . . .

. . .

They sit in their meadow, but the beach before it is piled with boneheaps

Of men now rotted away, and the skins shrivel upon them.

[Lattimore translation, Book XII, ll. 40-46]

In the story, Circe tells Odysseus that the Sirens are formidable creatures. They are beautiful and unimaginably seductive. With their voices, they lure men to their deaths. To her recollection, no man has survived an encounter with the Sirens.

According to Circe, the Sirens sit in a green field and will "warble" a man to death with the sweetness of their song. Circe doesn't give specifics on how this happens but warns Odysseus that these creatures are surrounded by dead men's bones.

Circe also tells Odysseus to stop up the ears of his men with wax, lest they be lured to their deaths. However, she tells him that he can listen on one condition: his men must bind him to the ship's mast as he stands on a crosspiece halfway up the mast. She also tells him that his men must bind him all the more if he begs to be loosened. While the text doesn't explain why Odysseus might want to listen to the Sirens, it's likely that the clever hero is curious about the Sirens' song and would take satisfaction in becoming the only man to ever survive having heard it.

For his part, Odysseus shares the words of Circe with his men. Then he stops up the ears of his men with wax, and they bind him to the ship's mast. As their ship passes the Sirens, the beautiful creatures sing. In their song, they say that no one has ever sailed past without stopping to listen.

The Sirens maintain that Odysseus and his men will be wiser after listening to them, and they also promise to tell the men "everything that is going to happen over the whole world." However, neither Odysseus nor his men stop their ship. They sail on with Odysseus tied to the mast.

In this way, both Odysseus and his men are saved from the clutches of the Sirens, and Odysseus is able to hear the Sirens' song and live to tell the tale. Later, after reconciling with Penelope, his wife, Odysseus regales her with stories about his close shave with the Sirens and his escape from various tragedies, terrors, and dangers.