The Annotated Alice
by Lewis Carroll
With very, very illuminating notes by Martin Gardner
There's a reason the Alice books have lasted so long. They're "whimsical" of course, and "imaginative," but that wasn't nearly enough. After all, Victorian England was just slopping over with treacly, sentimental juvenilia - Little Lord Fauntleroy, anyone? - so it wasn't as though Carroll (aka Charles Dodgson) was stepping into a desperate market.
What keeps them going, I think, is a darker undertone (who can forget Humpty's suggestion to Alice that "with proper assistance, you might have left off at seven") and the fact that so much of his madness had an order of its own - as Gardner points out, a specifically mathematical and logical order. Even when we don't understand Carroll's jokes directly, we sense there's more thought behind them - and Gardner's excellent notes lay it all out. It's well worth the $20.