In Act I, Scene II of The Tempest, the "airy Spirit" Ariel is ordered by Prospero to lead the shipwrecked Ferdinand to him. She does this by invisibly singing to gain his attention and guide him by the sound of her voice. The second stanza is of particular relevance to Ferdinand since his father drowned. These are the lines that come to mind. Hark! I hear them --

Full fathom five thy father lies;
Of his bones are coral made;
Those are pearls that were his eyes: