Notice how Golding juxtaposes the events on the lagoon with Ralph, Piggy, and the others—with Simon having an imagined conversation with the Lord of the Flies.— What is Golding’s purpose for this in Lord of the Flies?
Golding's purposeful juxtaposition of Simon's conversation with the Lord of the Flies against the other boys' conversation at the lagoon reinforces the author's central theme concerning the boys' descent into savagery. Simon's conversation with the Lord of the Flies centers around the true identity of the beast, which the fly-covered head mockingly reveals as himself:
"You knew, didn't you? That I'm part of you? Close, close, close! I'm the reason why it's no go? Why things are what they are?" (143)
This moment in the conversation underscores Simon's belief that the evil on the island emanated from the boys themselves, and that they were all in danger of reverting into savages. Simon had tried to explain this belief to the boys once before at one of the assemblies (in chapter six), but without any success. Now, in the dark and faced with the horrid Lord of the Flies, Simon's theory becomes more real than ever.
Golding perfectly times Simon's encounter with Ralph, Piggy, Samneric debating on the previous page on whether they should go to Jack's feast or not. The boys conversation reveals a true struggle between accepting savagery by going to Jack's feast or, as Ralph insists, maintaining the signal fire, which he deems the most important thing for rescue and returning to civilization. As the boys contemplate how to make the right decision, Bill observes:
Let's go to this feast and tell them the fire's hard on the rest of us. And the hunting and all that, being savages--I mean, it must be jolly good fun" (142)
Bill's comment reveals the temptation felt by himself and the other boys-- to drop their ties to civilization, to become savages and think of nothing but hunting anf fun. The struggle that the boys feel over choosing rescue and civilization or 'fun' savagery is reinforced by Simon's dark encounter with the Lord of the Flies; between the two scenes, Golding builds upon his theme of "mankind's essential illness" (89).