Istredd assumes that is Lucifer giving an example of two words that mean the same type of give and take. Darkness and light are things in his Sphere too, obviously, but they don't mean the same. And beyond that, moral purity is not a thing that really exists in his world. Anyone could be called good or evil, people tend to have their own moral compasses. It's a complicated Sphere.

"We tend to use the word channel more for it. I don't think any of us control Chaos, but we can use it. And it's dangerous when you can use it and you aren't trained, most people die." The rare exceptions become independent magic users, sometimes becoming corrupted by their relationship to Chaos.

"They can sense when someone is using magic and they come find us when we're young. It takes many years to train, and even while training people die, sometimes by only one small mistake." Meaning that he understands how dangerous Chaos is, it is very easy to die by it.