Readers under the sorting hat

These days, children often devour the entire Harry Potter series during their years at primary school. At the time of each publication, the character grew along with the readers: each volume saw Harry growing up. Based on a digital analysis of the books, it appears that the style of the books and the themes covered in the books changed along the way too. Sentences became longer and more complex. Slowly but surely, themes turned from food, school, and animals, to spiritual topics and death.