Aang: This is all my fault. It's the Avatar's job to protect the natural world. That's just as important as helping people and fighting Firebenders. How many more forests have died because I wasn't here? Because I don't know what I'm doing?

Katara: Gran Gran says... life is a cycle. And out of death comes new life. This will be a forest again. That's what you should see. Seeds for the future. Not past mistakes.