His Dark Materials is what a true trilogy should be - each successive book deepens the power of the story and builds an intricate crescendo of events and twists. In "The Subtle Knife," the attack on free will and knowledge continues, and the revelation of how far its reach has extended is astounding. Though we face that attack day-to-day in our world, Pullman's mastery is that he forces readers to reject their apathy about this and realize the horror of this attack, not just in this world but in every single parallel world stacked on top of each other. Much as I loved reading series like "The Chronicles of Narnia" growing up, this trilogy is setting itself up to be a welcome antithesis to the ideology of those kinds of series.