I'm trying to think back to how I felt when I first read
A Wrinkle in Time. Was it the first children's science fiction book I ever read? Maybe. The first heartbreaking book? Quite possibly. I can't think of anything really profound to say, I just loved it. The sequel too, though I know I'm kind of alone there.
I remember ... how less than clear-cut it was. Conversations that didn't just go from A to B. Undercurrents, subtext, a challenge to the reader's intelligence. I remember understanding the tesseract concept one time I read it, and then not again, and always trying to get that back. And understanding who the "witches" were and then losing that understanding too, in a positively Peter-Panesque fashion.
I remember crying at the end, many, many times. Every time.