The Age of Innocence and the Age of Anxiety
It is theoretically possible but practically impossible to read the Harry Potter books as intended. There’s a steady upward progression in maturity through the series. From books one through five (which had to be set in 11.5-point type, rather than 12), each is longer than the one before, and also more demanding of its readers. After book five, Rowling eased up a bit on the length, but also set the “dark themes” dial even higher.
Let’s look at the bodies for an example. Book four’s signature death is Cedric Diggory, a nice boy but not a central character. Book five’s is Sirius Black, a fan favorite. Book six takes away Dumbledore, but he also suffers first, in a particularly harrowing scene in the horcrux cave. And book seven is, of course, a veritable bloodbath.
In light of all this, the most appropriate age for a reader is probably Harry’s age: a moving target. Book one is a nice read for an 11-year-old; 17-year-olds seem about the right age to grok book seven. You can be off a bit in either direction. The dementors in book three probably won’t give a reasonably stout-hearted 11-year-old nightmares; the books have delighted not just 17-year-olds but also 70-year-olds. But there are definitely some losses as you get farther out. You really have to be 11 or close to it not to find the first book (considered on its own) a little twee and more than a little derivative. And the adolescent agnst of book five is probably going to be lost on anyone who’s never (yet) been a teenager.
The books didn’t come out at the one-a-year pace needed to pull off this schedule. They were on track up through book four, but book five took three years, and six and seven took two apiece. The 11-year-old who started the annual journey to Hogwarts with his contemporary Harry is 21 now, a good four years older than the wizard.
Now that all seven volumes are out, it’s actually harder to set a good pace. Potterphiles can testify that the craving for the next book is most intense right after finishing the previous one. Knowing that the book was out there ready and waiting for you, could you hold off a year? More to the point, could you tell your Harry-crazed kid to hold off a year? Six times? You might just barely be able to keep the existence of the later books a secret from an 11-year old, but once you bring out the second, the jig is pretty much up. Your 12-year-old knows that there are seven years at Hogwarts, and if there was a book two, there’re probably books three through seven lurking out there, too.
Besides, if her analytical mind doesn’t spoil the surprise, her friends and classmates probably will. Even leaving aside the movies, not having read the later Harry Potter books is going to be the literary equivalent of unilateral disarmament at least until everyone in this generation who grew up on the Harry Potter novels is past the age of reproduction. There are strong pressures to go as far through the series as you can stomach once you start it at all, and so the question becomes at what age to start. No age is ideal; books of very different tone are compressed together. You could be well-suited for the first two, the middle two, or the last three, but you’re probably not well-suited to all seven at the same time.
I can think of various compromises, but none of them truly solve the problem. Starting at age 11, you could probably get up through book three; if the scary bits didn’t convince you to lay low for a while, book four’s sheer bulk might. In a few years, say at age 13 or 14, you could pick up again and read through the end. Okay, but still not quite the way it’s meant to be done. Reading them as an adult and regressing to childhood during the experience may well be the best way to go.