For a long time when I was a kid, A Wrinkle In Time was my favorite book. I haven't read it in 30 years, but I still remember so much about it: the opening scene with Meg in her bed under the quilt and the storm raging outside, her brother Charles Wallace sitting in the kitchen in his footie pajamas, the father in his lab, the old women of increasing mysteriousness (Mrs. Whosit, Mrs. Whatsit, and who was the other? The really weird one), the word tesseract, the crazy thing that happens to Charles Wallace's eyes in the end.
I had tried to read it when I was younger, seven or eight or so, but it was too hard. Still, I found it intriguing enough that I took it out of the library a year later and that time I got through it. It made me feel smart and grown up -- it's a novel of ideas for children.
Madeleine L'Engle didn't condescend to children -- she knew how much they can grasp if the story is empathically and intelligently told. She leaves behind a body of work and a legacy we should all envy.