What's Prescriptive in the New Testament?

Bobbi Kristina Smith: It's not always immediately clear what's descriptive, what's prescriptive in the New Testament. She says it requires a certain sophistication of hermeneutic to read through these occasional letters. Would there be an argument to write a sort of middle level book on this particular topic with that? "I certainly think it's a topic that could do with fuller treatment," she says.