By highlighting Harry Potter's impact, I'm not making quite the same point as people who argue that JK Rowling's greatest merit is that she "gets children reading". (Though, if you believe reading boosts children's writing, then that is a significant achievement. Remember how we used to complain children didn't read? We don't now).
In fact her effect on children's imagination and language has been more powerful than that. The books are worth staying up half the night for. What happens in them matters. There were howls of anguish in my daughter's classroom, when an inconsiderate child let slip who dies in The Order of the Phoenix. Adults have begged me not to tell.
All this isn't just reading. It is a shared experience with a book at its heart. It is the kind of commonality Churchill's broadcasts created in wartime. Rowling has enabled millions across boundaries of age, culture and class, to take the same imaginative journey. A lightning scar and pair of glasses is all it takes for complete strangers to know that they are part of a literary community - a community to which it is not only normal, but cool, to belong.
And - despite the vile merchandising - this is not a passive, consumerist community either. Many Potter readers also become, in their heads at least, Harry Potter writers. They put their minds to what will happen next. They search for clues, use deduction, and try to put themselves inside Rowling's mind. Can Snape be trusted? Will Ron and Hermione become an item?
They are engaged in active reading, using exactly the predictive, interpretative skills the literacy hour requires. Only they are not doing it because it is prescribed for the second week of Year 4 term 3. Their creativity is spontaneously generated by characters they love and hate, and by knuckle-chewing narrative tension.
And that's not all. Rowling's other powerful message to readers is that writers can push language around. You can invent new words - quidditch, flobberworm - and other people start to use them. (Muggle now graces the OED). You can make puns (Diagon Alley) or mock with parody (attractive blonde Rita Skeeter's tabloidese; Professor Umbridge's scarily accurate edu-bureaucrat-speak).
You can also - and this is particularly powerful for children - find images for things for which you have no words. Rowling's grisly Dementors are an extraordinary embodiment of depression - something children may experience but for which, without her, they might never have been able to express.
I love the fact that my children can visualise a centaur, a boggart, a troll: nouns which meant nothing to them before. I like the rain when it means they point at my glasses and shout Impervius.
Of course there are linguistic infelicities and clunking plot lines in some of the books. But there are also characters who leap off the page, false trails that make your brain ache, and a whole weird world into which you can escape. The last time people queued in the streets for each new episode of a publishing sensation was when Dickens topped the bestseller list. And we make children read him.
Karen Gold is an education journalist