For those of you who like a little sybmolism in your games, how about the medieval Christian idea of the Great Chain of Being? The idea was that all of Creation was arranged in a several "chains", with each link in the chain representing something in creation, of a specific group. Each link was synonymous to things of other chains at the same level. For example, the top of the chain for Man were Kings, for animals Lions, and trees Oaks. So, when you saw an oak tree, you were supposed to associate it with royalty and lions.
Everything had a place in the chain. They were supposed to protect those below them, and support those above them.
The most meta of those chains were the orders of creation. Rocks were at the bottom, with plants above them, and then the animals, and then man, and lastly, the Angels. Each part of creation had its role and ability. The earth's ability was that it was a base, its durability. Plants grew, and provided for all above them in animals. Animals reproduced(that was their thing, really), and provided food for Man. Man's gift was knowledge, and that Man could reason and innovate.
The Angel's gift was really the interesting one. They could 'intuit' whatever was good or evil, immediately. They didn't need to know what would glorify God, they just intuited it.
There was a really interesting book I read a while back, that goes into how much symbolism there really was in the Medieval period with the Chain.