A minute past Friday’s midnight was the release date for “Harry Potter and the Half-Blood Prince.” And according to J.K. Rowling’s democratic wishes, everybody, whether child or book reviewer, would get their copy at the same time. Frustrating, but fair. (I’m still wondering how Michiko Kakutani got her review in Saturday morning’s New York Times: Rita Skeeter’s QuikQuote Quill or fishy influence at the Ministry of Scholastic?)

Speculation in my neighborhood was rife about how I would get my copy. Some children liked the notion of delivery by apparated house elf. My son wanted a commando to parachute down on our roof. I was plumping for a silent black car carrying a messenger with a time-release briefcase chained to his right hand. We put up a sign with big arrows pointing to our front door, 12:01 came, and – nothing happened. But the UPS guy was quite friendly when he showed up at 10:30 Saturday morning.

While I was tapping my fingers, I started to ask myself similar questions about the book itself. Could it really deliver? Or would it, too, turn out to be a squib?

Well, the book finally came, I read, and it conquered.

Harry’s friend Ron’s mother has a magical clock to let her know what her large family is up to. In place of numbers, it’s got labels for home, school, lost, prison, and suchlike: “Every single one of its nine hands was now pointing at ‘mortal peril.'” The Dark wizards under the sway of Lord Voldemort are regaining their rule of terror. There are tortures, deaths, and “disappearances.” They’re making alliances with dementors, giants, and werewolves. Dark magic can conjure uncanny cohorts, too, like Inferi, animated corpses emptied of life but able to be filled with the will of a Dark wizard.

The magical world, faced with such foes, has replaced the former minister of magic, the Neville Chamberlain-like Cornelius Fudge, with the more formidable Rufus Scrimgeour. But victory can’t be won unless Voldemort dies. And since he has taken the Dark Arts further than any wizard before him, figuring out how to kill him is the mystery of this tale.

The battle between good and evil is all very well, but between skirmishes Harry has been learning to deal with ordinary moral shabbiness and villainy. Every year there’s a new master for the Defense Against the Dark Arts class, so every year Harry and his friends face new challenges of more than just subject matter. Professor Quirrell taught them the dangers of weakness, Gilderoy Lockhart the dangers of vanity.

As the students get older, the lessons get more complicated though, as in the cases of professors Lupin and Moody, where what you see is definitely not what you get. Most recently, Dolores Umbridge could have given Mr. Brocklehurst of “Jane Eyre” lessons in self-satisfied pettiness swollen into malice and injustice.

The new master this year is Horace Slughorn, a tuft-hunter uncannily talented at collecting students who later become influential – and remember to show their gratitude. The Dickensian name is most suitable for this man who, as Dumbledore notes, “has never wanted to occupy the throne himself; he prefers the backseat – more room to spread out, you see.”

Living parasitically and comfortably on the talents of others, Slughorn is a type that recurs often enough in English fiction (Sillery in Anthony Powell’s “Dance to the Music of Time” is perhaps the most famous example) that one assumes there are many real-life prototypes. So Harry’s lessons here might prove valuable for readers, too.

“The Half-Blood Prince” (Arthur A. Levine Books, 672 pages, $29.99) has plenty of thrills, including the obligatory Quidditch, but the real momentum of the book is more internal. In the previous book, Harry was tiresomely full of solipsistic spoutings – “YOU DON’T KNOW HOW I FEEL,” he bellowed hither and yon. It’s a relief to announce that the all caps dialogue count is way down. Indeed, Harry is beginning to teach himself that sometimes human travails require silence: “Determined as he was to remain friends with both Ron and Hermione, he was spending a lot of time with his mouth shut tight.”

The external demands of rule-following have been replaced by inner discipline, even if Harry’s boldness is still a close cousin to foolhardiness, as his reliance on the spells in an annotated textbook reminds us. Harry’s education has included book learning and practical learning, but he’s been absorbing the lessons of the heart as well – kindness, courage, loyalty, and the virtue that Dumbledore places above all others: love.

While we learn a lot about the early Voldemort in this book, the real discovery is Dumbledore. At the end of the last volume, Dumbledore confessed to Harry that he was guilty of making “an old man’s mistake”: “I cared more for your happiness than your knowing the truth.” Now they are going to be fellow explorers in “the thickets of wildest guesswork” to figure out what makes Voldemort tick, and what might make him stop ticking:

“From here on in, Harry, I may be as woefully wrong as Humphrey Belcher, who believed the time was ripe for a cheese cauldron.”

“But you think you’re right?” said Harry.

“Naturally I do, but as I have already proven to you, I make mistakes like the next man. In fact, being – forgive me – rather cleverer than most men, my mistakes tend to be correspondingly huger.”

Their unexplored territory is the past, where family psychodramas, especially the fates of mothers, turn out to be increasingly important. Ms. Rowling raised the painful conundrum of fate versus free will in a prophecy that inextricably joins Harry and Voldemort in a fight to the death. The lessons Dumbledore feels most passionate about circle around notions of self-fulfilling prophecy: “Voldemort himself created his worst enemy, just as tyrants everywhere do! … He heard the prophecy and he leapt into action, with the result that he not only handpicked the man most likely to finish him, he handed him uniquely deadly weapons!”

Dumbledore sometimes gets compared to Gandalf, sometimes to Obi-Wan Kenobi. The Dumbledore that emerges in Harry’s private tutorials has shades of Socrates. He leads Harry to sift the sources of evidence, to question assumptions, to recognize his own evasions. “Know thyself,” indeed. By the end of the novel, Harry’s increasing knowledge of the competing tugs of his own heart leads him to feel a measure of sympathetic understanding for Voldemort, the killer of his parents and many other people, and even, closer to Hogwarts, his old enemy Draco Malfoy.

Harry still, however, feels no sympathy let alone forgiveness for Severus Snape, who’s back, possibly with a vengeance. Snape has been involved in a spy/counterspy game, secretly aiding Dumbledore’s Order of the Phoenix while apparently serving the Dark Lord. But what should we think when we hear him in covert conversation with Bellatrix Lestrange, the killer of Harry’s godfather, telling her, “[Y]ou overlook Dumbledore’s greatest weakness: He has to believe the best of people.” What precisely lies behind his Unbreakable Vow to Narcissa Malfoy?

Snape’s role is getting ever more shadowy, and we’ve yet to have all of his motivations laid out for us. Snape’s place between Voldemort and Dumbledore has too many unknowns to be calculated. Dumbledore has always trusted Snape; Harry never has. The final volume, which promises to leave behind the structure of the school story for the knightly quest, will show who is right.

Ms. Mullen last wrote in these pages on manners.