How to Divide Up a Book

How do you divide up a book? If you're going to go through, say the gospel of Mark and you like 15 weeks based on these other considerations. Well, outlines and better commentaries are useful. And if I look at six commentaries and they're all agreeing on these 14 divisions, but then it's entering there, two divisions that they disagree on, I'll spend my time looking at those two divisions and trying to make my own decisions about where I think things had best to fall.