Edit: Augh! I hate the whole quote problem.
Like I said, I read quite a few articles by scholars in the field for my fantasy class. I don't have time tonight to sum up; will do that tomorrow. Here are the references:
This one's considered a standard in the field, at least as far as children's fantasy goes:
Sheila Egoff, "The Matter of Fantasy" from Worlds Within: Children's Fantasy from the Middle Ages to Today (1988)
Here are some others:
C. W. Sullivan III, "Fantasy" from Stories and Society: Children's Literature in its Social Context (1992)
Diana Waggoner, "Theory of Fantasy" from The Hills of Faraway: A Guide to Fantasy (1978)
Susan Cooper, "Escaping into Ourselves" from Celebrating Children's Books (edited by Betsy Hearne and Marilyn Kaye) (1981)
Elliot Gose, "Introduction" from Mere Creatures: A Study of Modern Fantasy Tales for Children (1988)
Jean Murray Walker, "High Fantasy, Rites of Passage, and Cultural Value." In Teaching Children's Literature: Issues, Pedagogy, Resources (1992)