1) Those written for young people and of interest and relevance primarily, or exclusively, to young people (e.g., the Sweet Valley High books);
2) Those written for adults and of interest and relevance only to adults (e.g., Nabokov’s novels);
3) Those written for adults that are also sufficiently accessible that they can be interesting to young people (e.g., several Dickens novels);
4) Those written for young people that are also sufficiently well-crafted and thoughtful that they can be interesting to adults.
I’ve been thinking about this again because I recently re-read Diana Wynne Jones’s The Magicians of Caprona, which is simply a glorious novel by ay standard you choose to apply. If you haven’t read it, please treat yourself as soon as possible.
That is all.