Piggy's glasses become a symbol for the blindness of the boys and a key to understanding why the boys are blind. At first, when Piggy's glasses are intact upon his face, Piggy can reason clearly. He knows that rescue is important. He knows that order is important. He cautions the boys against acting "like a bunch of kids," when they suddenly rush to build a signal fire that gets out of hand, resulting in the death of one.
In Chapter 4, however, Jack breaks one side of Piggy's glasses. As the fear of the beastie on the island grows, Jack's power also increases, and the chasm between the hunters and the builders of shelters grows wider. Ralph's ability to control the group becomes diminished, so much so he tells Piggy
"Fat lot of good we are . . .Three blind mice. I'll give up."
The group has become so dysfunctional that Ralph feels as if he, Piggy, and Simon may as well be blind. Ralph cannot see a solution to the problems that are confronting the boys on the island. And Piggy is rendered powerless to help him.
When Jack's group steals Piggy's glasses, the strength of rational thought is completely diminished. The light of civilized thinking, law and order is snuffed out, as the savages take over the island. Piggy asks the savages before he is killed,
"Which is better, law and rescue, or hunting and breaking things up?"
Piggy receives his answer from the fatal blow of the rock that Roger sends over the cliff. The boys choose blindness--ignorance, savagery, chaos--over the clarity of reason and rationality.
Other symbols emphasize the boys' blindness to rationality. The chapter entitled "Shadows and Tall Trees" is particularly important in showing the boy's blindness to the truth of the beastie. In this chapter, Jack, Ralph, and Roger become convinced that there is a beastie on the island, mistaking the dead parachutist for a monster. The darkness obscures their vision of the truth. Another fatal mistake also takes place in darkness when the boys mistake Simon for the beastie.
The boys are blinded by fear, by their susceptibility to violence, by poor judgment, by their incapability of maintaining order, by their impulsiveness, and by their lack of capable leadership.
In Lord of the Flies, the boys are indeed blinded by their fears; they are also blinded by their desire for power and their immaturity and ignorance. The most prominent showing of the boys' irrational fear surrounds the hunt for the "beastie." The boys do not try to understand the inner workings of the island, and as a result, the fear of the unknown blows out of proportion. The "beastie" takes over the boys' minds, and their fear leads to violence.
In addition to fear, the boys are also blinded by their desire for power. The group splits because the boys have different ideas about how to be successful in their survival on the island. Rather than try to mediate their differences, the boys want to prove that their way is the better way, so they split up. They are blind to the fact that the group will likely be more successful in a unified large number; however, they do not consider this in their quest for power.
Finally, the boys are blinded by their immaturity and ignorance. They do not have any experience to support their decisions and they do not understand the possible consequences of their actions. So they enter into situations without truly understanding what the results might be.