Rats and people
These rodents are all personified, which means that people are being shown to be similar to animals. The rodents are something that many people would fear, as many people are phobic about mice and rats, but the book makes them main characters, symbolizing the similarities between animals and people.
Medicine and wellness
The quest for medicine begins this story, making the medicine a symbol for love, because Mrs. Frisby sacrifices a lot to get Timothy the medicine he needs. Love is depicted as getting what someone needs for them when they are unable to get it themselves, no matter the cost of time or possessions. She loves Timothy by solving his problems, not just by offering sympathy.
Food and survival
The quest for medicine is similar to the quest for food that symbolizes survival, literally. They work together to make sure all the community has food, but that is a complicated problem. They quest for food is a symbol for human economy, because people get jobs and earn money to get food for their families, making the two more similar than different. Both people and mice need the same basic things: Food, shelter, and community.
Reading as a magic power
An animal that can read is like a magic animal, but in this story, that's exactly what happens. This symbolizes the strange human power of the written word, of language and story, and of reading. The importance of reading is that they learn more information that helps them to be successful when various problems arise. They have to read to realize that they need to escape. They have to read to understand they are in a dangerous situation.
The Dragon
The Dragon is a mystic reminder of mystery and fantasy, so perhaps one might say it symbolizes curiosity or amazement. Perhaps it also symbolizes the secret importance of community and love, because the Dragon is something spiritual and quasi-animalistic. Just like humans are animals with other aspects, the Dragon is like an animal with aspects all its own. The Dragon symbolizes mystery and investigation.
