Simon was hallucinating like Michaela mentioned, due to lack of water and food and overexposure to the sun. That maybe he was imagining the pig's head on the stake talking to him. After reading it over a couple times and thinking about it for a while i realized that Simon's recognition was actually that the beast was them themselves like you all concluded. The boys started off with some civilization, the conch brought them structure and leadership and by picking Ralph as their leader brought some means of government. However, this structure soons starts to wear off. In the beginning, when the conch is first discovered, the author describes its colors as yellow and pink, showing its bright and distinct--important. As time goes on and many meetings are called, the conch starts to loose its significance or importance, the author then describes the conchs shell as white or almost transparent. Although literally meaning that its color has changed from sun exposure you can also look at it deeper and realize its importance and need for it is wearing off as well. Boys at these meetings talk more and more out of turn, not thinking of the rule of the conch. And finally i think Jack leaving the group and refusing to conform to Ralph's leadership is what really shows Simon how their structure is falling apart. Jack leaves to become his own leader, something that can't happen in a strong civilization, and boys follow him after hearing the advantages of what Jack has to offer. After the boys chase and kill the pig and stake in the ground, Simon is the first to realize that they are now completely uncivilized. He can see that without the structure, the boys are resulting back to their animal, primate ways. Jack has become power thirsty, resulting in violence and killing...what will come next? I agree with Syd and Jess that as the chapters go on, Simon will exclude himself from the rest, knowing what is becoming of them. Simon has always seemed a little different than the other boys, mysterious. I also had the same thought as you, Jess, that maybe Jack's group, becoming so insane and animal-like, will attack Ralphs's group. Remember when the boys are joking around with Robert in the middle pretending to be the pig and Jack purposely stabs Robert with the butt of the spear and then "jokes" about killing a littlun in their game? Maybe the author is using this to forshadow that some kind of killing like this will actually happen. It is showing Jack's increasingly violent behavior.