Throughout the novel, the boys "attach" mentally and emotionally to various items. For instance, the conch symbolizes a form of stability and authority, as well as a vague sense of democracy. Whoever is holding the conch is the only one allowed to speak; when Jack throws out the concept, the boys--particularly those in Ralph's camp--are shaken.
Piggy's glasses are also symbolic; as the boy with the clearest head, he has the best understanding of their situation. He knows they are stranded, that no one knows where they are, and that being as they have no adults around, they need to elect a leader they can all trust. Shortly after his glasses are broken, the frenzies begin. Jack begins to revolt and play on the fear of the younger children, and eventually breaks off with his own group.
The book itself is allegorical, a symbol of civilization versus savagery. The boys were from a civilized prep school and once taken out of their highly-structured environment and dropped into nature, the primal overtakes them.