Hanna found me a copy of Alison Lurie's 1990 book Not in Front of the Grown-Ups: Subversive Children's Literature on the $1 cart at brookline booksmith, and yesterday I started reading it and came across this quote.
I think we should...take children's literature seriously because it is sometimes subversive: because its values are not always those of the conventional adult world. Of course, in a sense much great literature is subversive, since its very existence implies that what matters is art, imagination, and truth. In what we call the real world, on the other hand, what usually counts is money, power, and public success.
The great subversive works in children's literature suggest that there are other views of human life besides those of the shopping mall and the corporation. They mock current assumptions and express the imaginative, expressive, noncommercial world in its simplest, purest form. They appeal to the imaginative, questioning, rebellious child within all of us, renew our instinctive energy, and act as a force for change. That is why such literature is worthy of our attention and will endure long after more conventional tales have been forgotten.1
1 Alison Lurie, Not in Front of the Grown-Ups: Subversive Children's Literature (London: Sphere Books, 1990), xi.
UPDATE: Reader fairbetty has alerted me in comments to the fact that the American edition of this book was published under the slightly different title of Don't Tell the Grown-Ups: The Subversive Power of Children's Literature.