“Of course I’m Meg,” Ms. L’Engle said about the beloved protagonist of “A Wrinkle in Time.”

The St. James Guide to Children’s Writers called Ms. L’Engle “one of the truly important writers of juvenile fiction in recent decades.” Such accolades did not come from pulling punches. “Wrinkle” has been one of the most banned books in the United States, accused by religious conservatives of offering an inaccurate portrayal of God and nurturing in the young an unholy belief in myth and fantasy.

The book uses concepts that Ms. L’Engle said she had plucked from Einstein’s theory of relativity and Planck’s quantum theory, almost flaunting her frequent assertion that children’s literature is literature too difficult for adults to understand.