The little details should have given Snape away

What was I thinking? How did I miss this? How did I fail to ask questions?

In the long passage in The Half-Blood Prince in which Dumbledore and Harry discuss the implications of the full Slughorn memory and the fact that Voldemort appears to be planning to make no fewer than six Horcruxes, the Head Master makes several comments that should, in my numerous earlier readings of the book, have made me stop and ask questions.

"When Voldemort discovered that the diary had been mutilated and robbed of all its powers, I am told that his anger was terrible to behold," Voldemort tells Harry at one point in the conversation.

Wait a minute, I should have said. Hold on there, Dumbledore. Who told you how Voldemort reacted to the news that Lucius Malfoy had permitted the diary to be destroyed? Who was there to "behold" Voldemort's terrible anger and then tell you about it?

But I didn't. I missed it. I failed to see the hint that J.K. Rowling laid down so subtly that, no matter what I saw and heard in Chapter Two, Severus Snape was actually still working for Dumbledore.

Who else could have given Dumbledore this tidbit of information from the inner sanctum of the Dark Lord? Who else could possibly have been there to behold the incident and then report it back to the Hogwarts Head Master?

Later in the same scene, Dumbledore drops another clue: "I understand that Voldemort had told him [Lucius Malfoy] the diary would cause the Chamber of Secrets to reopen, because it was cleverly enchanted."

'You understand from whom?' I should have asked. 'That's pretty specific knowledge of the details of what the Dark Lord said to one of this closest companions about one of his most important possessions. You couldn't become acquainted with that level of detail from a simple rumour, from third-hand reports.'

Remarkable. It's one of the most amazing things about Rowling as a writer of suspense: she has this uncanny knack of dropping little hints, tiny clues, minuscule details innocuously into seemingly much more important passages so that the reader does not pick up on them on first, second or third read, yet might some day (like today) realize just how important those hints, clues and details are to the story.

She makes her stories so exciting that it is impossible to slow yourself down and pay attention to the minute details yet she rewards such attention to detail with clear indications of what is really going on.