1. Human Ingenuity
1.1. "'His specs - use them as burning glasses!' Piggy was surrounded before he could look away." [38]
1.1.1. This relates to the theme of human ingenuity, which is symbolized in Piggy's glasses, in the sense that the boys use the glasses in order to light a fire.
1.1.2. By using Piggy's glasses, the boys are using innovation to survive, and are applying their knowledge to useful circumstances.
1.2. "Then to his surprise, Ralph went to Piggy and took the glasses from him... 'I'll bring 'em back.'" [67/73]
1.2.1. As Ralph and the others continuously take Piggy's glasses and use them to light the fire, it shows how they are utilizing this tool as often as possible.
1.2.2. This also shows that the boys have begun to rely on Piggy's glasses to create fire, which is used for many different things, and without his glasses, they would no longer be able to function on the island the same way.
1.3. "'You could have had fire whenever you wanted wanted. But you didn't. You came sneaking up like a thief and stole Piggy's glasses!'" [163/188]
1.3.1. By the end of the book, the specs have become more desirable, since the group of boys have split into different clans. At this point, they no longer become a symbol of ingenuity, but instead have caused fights.
1.3.2. Since the glasses were initially used as a result of the boys' ingenuity and creativity, they want to continue using them this way, but are unable to once the glasses are targeted by both tribes.
2. Knowledge
2.1. "'So we've got to think.' Piggy took off his damaged glasses and cleaned the remaining lens." [94/104]
2.1.1. Piggy's glasses are mentioned multiple times while Piggy is thinking. The specs help to communicate this because Piggy is described as being cleaned off while thinking.
2.1.2. This shows that the glasses come into play while Piggy, an intelligent character, is thinking or making decisions. Furthermore, this shows that the glasses symbolize knowledge due to the fact that they can be seen during times of thought.
2.2. "Piggy came with it, in shorts and shirt, labouring cautiously out of the forest with the evening sunlight gleaming from his glasses." [38]
2.2.1. Throughout the story, Piggy's glasses are constantly "flashing" and are said to shine from the light reflecting through them. This light can be interpreted as a reference to Piggy's wisdom, as light is often seen as a symbol of knowledge.
2.2.2. By using Piggy's glasses as a symbol of knowledge and constantly describing them as being lit up from the sunlight, or flashing whenever he is about to speak, it shows that Piggy always has an idea of what to do next and therefore is one of the characters with the most knowledge.
2.3. "'I've only got one eye now. You ought to know that, Ralph." [145]
2.3.1. When Simon is killed by the boys after being mistaken for the beast, Piggy blames his lack of help on the fact that he cannot see with only one working lens.
2.3.2. This shows that, without his glasses, Piggy is unable to see clearly and therefore cannot comprehend or know everything in the same way as he could prior to his glasses being broken. From this, one can conclude that Piggy's ability to see was based on his glasses, which was the same item that allowed him to understand and learn more about his surroundings. Without the aid of his glasses, Piggy can no longer fully exercise the potential of knowledge.
3. Order
3.1. "He took off his glasses and looked vainly for something with which to clean them." [12]
3.1.1. Piggy is constantly known to remove his glasses and attempt to clean them. Since the glasses may represent knowledge and keeping order, this may be symbolic of Piggy trying to maintain civilization on the island.
3.1.2. Since Piggy never succumbed to the boys' savagery and tribal ways, he becomes one of the only characters who consistently tried to keep the peace and bring the group back to a societal and orderly state. By cleaning his glasses, he can be interpreted as trying his best to prevent the group from destroying the order they had built.
3.2. "Jack smacked Piggy's head. Piggy's glasses flew off and tinkled on the rocks. Piggy cried out in terror: 'My specs!'... 'One side's broken.'" [66/72]
3.2.1. Once the glasses are broken, Piggy is no longer able to use them for himself. This shows how Jack's savage nature has affected and disrupted the order on the island.
3.2.2. Now that the glasses are no longer usable to Piggy or the other boys, they have become a symbol of the loss of order and society on the island. Because they are unusable, they now represent the distance between the boys and civilization.
3.3. "'You pinched Piggy's specs,' said Ralph, breathlessly. 'You've got to give them back.'" [163]
3.3.1. After Jack steals Piggy's glasses, it becomes apparent that this could be a symbol for the destruction of peace and order within the island.
3.3.2. By stealing the item that symbolizes knowledge, order, and ingenuity, Jack has demonstrated how far from civilization the boys have come. Instead, he has taken the glasses to use purely for his own reasons and without thinking of the others on the island, which shows how the unity that was established at the beginning of the book has long since faded away.