In the ' Lord of the Flies' is Simon deluded and ill, or has he alone grasped the true nature of what is going on ?Consider the Lord of the Flies'...

In the novel, Simon faces the "pig's head on a stick"--the
Lord of the Flies, and falls into a trance.  Simon is not hallucinating; he is having a
vision.  The vision is his nsight about the beast.  The Lord of Flies tells Simon that
Simon knew all along who the beast was.  It is "not something you can hunt and kill." 
It is the savagery that lies within each of the boys.

The
facts of the novel support this idea.  The boys' most dangerous enemy comes not from
without but from within.  It is their carelessness, fear, power struggles,
and aggression that cause the turmoil on the island.  Simon is being tempted here.  He
can become savage as the others, and survive, or he can refuse and "they will do him." 
Only Simon seems to understand the nature of evil on the island, just as he is the only
one to ascertain the true nature of the beastie:  a dead man with a
parachute.