In this section from book 12 of the epic poem, Odysseus narrates his encounter with the Sirens. As his ship approached the island where the Sirens live, he notices that the winds calm and the waves no longer lap against the hull. Everything becomes still and silent. The winds do not help Odysseus's ship to cruise past the Sirens; instead, it is as though some power, larger than the mortals on board, stills everything in the natural environment so as to slow the progress of ships past the island.
This is why Odysseus suggests that "Some demon calm'd the air and smooth'd the deep, / Hush'd the loud winds, and charm'd the waves to sleep." Something supernatural seems to have happened here. He then takes this opportunity to stuff his men's ears with beeswax, as Circe told him to do, so that they will not be able to hear the Sirens singing.