Lord of the Flies?? Please Last Question I Got Left!?

Okay, I answered every other question and now I'm just stuck on one last question and it's the last one that I got left to answer. It's about the book, 'Lord of the Flies' it says,

While part of the party searching for the Beast, Simon realizes that the notion of the Beast that the other boys have does not make sense. A Beast sitting atop a mountain with claws, a Beast who did not leave tracks, could have easily caught the twins. Simon has a different picture of the Beast: "there rose before his inward sight the picture of a human at once heroic and sick." How does this picture relate to the Beast that Samneric saw? How does it relate to what Simon said earlier about the beast being "only us"?