The answer to this question can be found at the end of this chapter. Simon, just before Jack's tribe (which he has set up in opposition to Ralph and his leadership) raids the beach, Simon leaves the boys and returns to the jungle glade where he had gone before to contemplate the beauty of nature. Now, however, he finds the beauty of nature tainted by the presence of the pig's head impaled on a stake in the centre of the clearing. Simon is transfixed by the sight of the pig's head and sits down staring at it and the flies that are buzzing around the pig's head. As he becomes more and more rapt by the sight before him, in his mind it is as if the pig's head comes to life, speaking to Simon as "Lord of the Flies," terrifying Simon by telling him that there is no escape from him and that he will have some "fun" with Simon:
I'm warning you. I'm going to get angry. D'you see? You're not wanted. Understand? We are going to have fun on this island. Understand. We are giong to have fun on this island! So don't try it on, my poor misguided boy, or else--
Simon is of course absolutely terrified by this turn of events, and as the chapter ends, Simon loses consciousness with the immensity of his fear and confusion over what he has seen and heard.