Percy doesn't have many peaceful nights of sleep in this story. We quickly learn that his dreams are messengers from the gods and from Kronos, or perhaps they are the way his half-god self communicates and taps into the immortal world and into certain prophecies. He first dreams of an eagle and a horse fighting to the death on a beach – the eagle and the horse represent Zeus and Poseidon, respectively. This particular dream symbolizes the war that will take place if Zeus's master bolt is not returned, but, at the time, Percy has no idea that the gods exist or that he is a half-blood. Pay attention to Percy's other dreams. Who does he see in them? Where do they take place? Do people talk to him? Can he talk back? Is his ability to dream a sign of his power or of someone else's power over him?