In this scene, King Henry IV is in his palace at Westminster. It is the middle of the night and he is in his nightgown, but he is still awake and working on the paperwork of the war.
When he is left alone, King Henry begins to talk to himself and the audience. He says that he has extremely bad insomnia and that these days he cannot sleep at all. Bitterly, he realizes that even the poorest of his subjects can sleep at night in their tattered beds, but he, the wealthy king, is too weighed down by worry, remorse, and anxiety to be able to do so. He concludes that people in positions of power are usually less happy and carefree than the poor and simple.
The Earl of Warwick and the Earl of Surrey, to whom the King sent messages at the beginning of the scene, enter and interrupt him in his reverie (they wish him good morning, and the king, startled, learns that it is now past one).
The three discuss the nation's current state of affairs: they know that the Earl of Northumberland is considering waging war against them. (They do not yet know what we, the readers, have found out in II.iii: that Northumberland has decided against supporting the rebellion.) The king muses about how swiftly time flows, the years turn, and people change. Less than ten years ago, Northumberland was a good friend of King Richard II, the king who reigned before Henry IV. Eight years ago, Northumberland turned against Richard and helped Henry take the throne from him. And now, Northumberland has turned against Henry himself. King Richard had prophesied that this would happen, and King Henry is now disturbed at the realization that Richard had been right.
Warwick, however, points out to the king that Richard had simply guessed that Northumberland would prove a traitor because he had already betrayed Richard. King Henry agrees, and the conversation turns to the course of the war. There is a rumor that the rebels have fifty thousand men, but Warwick is sure that these are merely rumors and that the rebels have no more than half that number. Moreover, he has good news from the west: Owen Glendower, the leader of the rebellious Welsh guerrilla fighters, is dead, so the king will be able to focus his efforts on the English rebels. Since the king has been growing sicker lately, the lords urge him to go to bed. King Henry, regretting once again that this war has prevented him from joining the Crusades in Jerusalem, agrees.
Compared to the lowlifes and peasants of the play, the noblemen often speak in elevated and complex language. King Henry IV is the most elevated among them, and his monologues here are masterpieces of densely woven metaphor, wordplay, and imagery--and are often very difficult to follow, at least on the first reading. They are worth looking over more than once.
His opening monologue, a contemplation of how elusive sleep is to mighty kings, showcases the breadth and depth of Shakespeare's imagination. Starting with the complaint that he, lying peacefully in the cozy and "perfum'd chambers of the great" (12), cannot get any rest, King Henry goes on to imagine where sleep has landed tonight: in peasants' shacks, choked with smoke from the fire and interrupted with "buzzing night-flies" (11); or even with the boy at sea who, perched in the highest mast of the ship to keep watch amid the tumbling of the waves, the blowing of the wind, and the wet spray from the ocean, still manages to doze off (18-31). Henry asks rhetorically, "Canst thou, O partial sleep, give thy repose, / To the wet sea-boy in an hour so rude, / And in the calmest and most stillest night... / Deny it to a King?" (26-30). He closes the speech with one of the play's most famous lines, often quoted as a motto about the anxiety and discomfort that accompany great power: "Then happy low, lie down! / Uneasy lies the head that wears a crown" (30-31). This kind of speech--the dark and uneasy contemplations of a king, alone in the middle of the night, facing the darkness in his own soul--seems to have fascinated Shakespeare. (Similar speeches appear in Macbeth and Hamlet.)
The king's second speech, after the other noblemen come in, is also grand in scope. Northumberland's rebellion has caused him to think about his own earlier rebellion, eight years before, in which Northumberland was his ally. His realization of how everything changes causes the king to despair on a grand scale: he wishes he could get enough perspective to "read the book of fate" (45) and see how time has made mountains wear away, coastlines disappear into the ocean, and water covering dry land.
Richard also seems to be a worried by his memory of the prediction that King Richard II had made, when Henry himself overthrew him: that Northumberland would rise against Henry himself. (The events Henry recounts in the passage are covered in Shakespeare's Richard II, III.iii, and V.i.) Warwick calms Henry down by reminding him that Richard's prediction was not a difficult one in light of his betrayal by Northumberland. Still, the events of the past clearly loom over this play, haunting both Henry IV and his antagonists. The king's repetition of his desire to go to Jerusalem, for instance, is a theme continued from both Richard II and Henry IV, Part 1, which will eventually have its resolution in this play in IV.v.