Why symbols are important in Lord of the Flies?

The whole book is an allegory, which means that while it is telling one story on the surface, if you look deeper it is also telling another story. On the surface the book is a coming of age story about a group of boys on a tropical island and their descent into savage behaviour. The underlying story is that the boys represent all of mankind and the point is that within every person there is the capacity to do evil, to kill and hurt, to be a savage, that is just beneath the thin veneer of civilization. So, as two stories are being told at the same time everything has to work in both stories. The conch, which calls boys to the meetings, becomes a symbol of the system of democracy in the adult world. Piggy's glasses symbolise technology and intelligence. Almost everything in the book symbolises something.