In Philip Pullman's "The Subtle Knife," the narrative emphasizes urgency in the quest for two pivotal characters, a girl and a boy. The instruction to "waste no more time" suggests that their roles are critical to the unfolding events, and the reader is drawn into a sense of immediacy surrounding their search.

The phrase "You must play the serpent" hints at the themes of cunning and the complexity of choices that the protagonists must navigate. It suggests that their journey will involve deception, strategy, and the navigation of dangers, reinforcing the intricate dynamics of Pullman's richly woven fantasy world.