Typical of many works of Shakespeare, King Lear is written in a combination of prose and "blank" verse, or unrhymed iambic pentameter. The opening of the play is prose, and then the verse begins with Lear’s arrival in line 32 of Act 1, Scene 1. From there, the style shifts according to who's speaking and the gravity of what they're saying.
To that end, Shakespeare’s decision to switch between prose and verse is not random. As the play progresses, he uses verse and prose to convey subtle changes. Most notably, King Lear—the first character to speak in verse—begins to use prose more often as he descends into madness. In fact, a notable example of Shakespeare’s stylistic versatility in King Lear is his ability to convey madness, both real and pretend, to the audience. Many of the play's most memorable interactions come about when characters attempt to reason with their maddened peers, and Shakespeare is not bashful about using nonsensical words to achieve a humorous—or even disturbing—effect. In Act 3, Scene 4, Edgar, as Poor Tom, puts on quite a display:
Who gives any thing to Poor Tom, whom the foul fiend hath led through fire and through flame, through ford and whirlpool[...]. Bless thy five wits! Tom's a-cold. Oh, do-de, do-e, do-de. Bless thee from whirlwinds, star-blasting, and taking!
Shakespeare pays careful attention to the sonic effect of his language in this passage and uses strings of nonsense and careful alliteration (particularly of /f/ and /d/ sounds) to imbue the language with a power best suited to live performance. In King Lear, as in all of Shakespeare’s works, the ever-shifting style is used as a way to give the dialogue additional layers of meaning.