Philip Pullman's The Subtle Knife

Philip Pullman's The Subtle Knife, which I am enjoying but, a little like Pete before me, just beginning to tire of. I read the first book in the series very quickly, surprised by how much I enjoyed it, although part of me couldn't shake the CS Lewis associations. The second book I thought was miles better; really rather brilliant in places and demonstrating considerable depth and a willlingness to introduce complicated ideas and concepts. The third I find a bit more trying, perhaps partly because it is more of a fantasy novel than the second, and partly because I've read the three books in such quick succession that I'm a little fatigued. All the same, they are better books than I had imagined.