A "giant of a man" bursts into the shack. We will soon learn that the giant is Hagrid, "Keeper of Keys at Hogwarts." He recognizes Harry, although Harry does not recognize him, and gives the boy birthday greetings. He also gives Harry a chocolate cake, and knowledge about Hogwarts that Hagrid assumed Harry already knew. Uncle Vernon and Aunt Petunia already know this information, and try to stop Hagrid from sharing it, but they are no more successful than they were at trying to stop the mysterious letters in the previous chapter from coming. Hagrid informs Harry that he, Harry, is a wizard, and has been accepted into the seven-year academic program at Hogwarts School of Witchcraft and Wizardry. As Harry, confused and full of questions, looks on, Hagrid writes a note with quill and parchment to Professor Dumbledore and sends it to Hogwarts by way of "a real, live, rather ruffled-looking owl" that has been under his overcoat. Hagrid argues with the Dursleys about whether Harry will attend Hogwarts, and also rebukes them for lying to him about the circumstances of his parents' death. He tells Harry the truth: his parents, James and Lily Potter, were killed by the wicked, power-hungry wizard Voldemort (Hagrid doesn't like to say the evil wizard's name here any more than McGonagall did in Chapter 1) on Halloween, ten years previously. Voldemort tried to kill Harry, too, Hagrid says, but could not: "No one ever lived after he decided ter kill 'em, no one except you . . . ." And then, Voldemort vanished: "Most of us reckon he's still out there somewhere but lost his powers . . . . There was somethin' goin' on that night he hadn't counted on." As Hagrid tells Harry the story of his past, Harry sees-not for the first time in his life-a blinding green flash of light, and hears "a high, cold, cruel laugh." On the other hand, he also now understands why strange things have always happened around him (such as the incident at the zoo in Chapter 2). When Uncle Vernon calls Dumbledore (Hogwarts' headmaster) a "crackpot old fool," Hagrid loses his temper and gives Dudley a magical pig's tail. The Dursleys race into the shack's other room, leaving Harry alone with Hagrid. Hagrid confesses he is not supposed to perform magic; in fact, he was expelled from Hogwarts in his third year, although he will not tell Harry why. Dumbledore let Hagrid stay on as gamekeeper. Hagrid covers Harry with his great coat, and they leave to get Harry ready for his new life at Hogwarts.
In Chapter 4, Hagrid delivers what scholar of world mythology Joseph Campbell identifies as the "summons to adventure." As he explained to Bill Moyers in The Power of Myth (New York: Doubleday, 1988), "All these different mythologies give us the same essential quest. You leave the world that you're in and go into a depth or into a distance or up to a height" (p. 129). Harry's quest will involve all three. Notably, Campbell cites Telemachus from Homer's Odyssey has a hero who is summoned to find his father, commenting, "That father quest is a major hero adventure for young people. That is the adventure of finding what your career is, what your nature is, what your source is. You undertake that intentionally" (p. 129). Readers will see how Campbell's analysis of the summons to the father quest applies to Harry, given Hagrid's revelation about Harry's father (and mother) in Chapter 4 (let alone Harry's overarching quest for knowledge about and experience of his parents, from the Mirror of Esired in the present volume, to the conjured patronus of Prisoner of Azkaban, to the vision of his father as a schoolboy at Hogwarts in Order of the Phoenix-and, no doubt, beyond, as more volumes in the series appear). Understanding Harry's summons out of the Muggle world and into the magical world as a quest for knowledge of father, and, thus, knowledge of self, opens new insights into Rowling's work. Far from being simply entertaining books for children, her novels tap into deeply-engrained archetypes and mythic motifs, helping account for their widespread popularity and critical acclaim. Chapter 4 also illustrates that the death of Harry's parents, and his escape from Voldemort, is never far from him. This event, which occurred "off-stage," concurrent with the events of Chapter 1, nevertheless shapes much of what follows. Rowling's return, throughout the series, to this fundamental event raises important questions of how much the past determines our present with which readers should wrestle.