What does the fox stand for in The Little Prince?

The Fox, or le renard in the French version, is a new-found friend to the Prince. He learns a very important lesson from taming and befriending the fox:

It is the time that we take to care for and understand those precious to us that MAKES them precious to us.

For example, you may see a normal boy amongst hundred of others -- he is nothing special to you. However, if you take the time and responsibility of befriending said boy and learning to care for him, he cannot simply be replaced by another.

The Fox teaches us the true value of people and things that we call our own.