How does William Golding use the “beast” in the novel as a whole?

Simon says: “Maybe there is a beast.”
Ralph says: “But there isn’t a beast.”
Jack says: “We’ll make sure when we go hunting.”
How does William Golding use the “beast” in the novel as a whole? You may want to consider:
what the “beast” symbolizes
the way the boys’ ideas about the “beast” change
what effect the “beast” has on the boys.