The impossible to decipher.

This professor acts all nice and genial. He says he doesn't care about attendance and about reference books. The most important part is that "the subject must be understood". But then you get your marks. And yes you've got a big,fat D.  So why did he act all cool. We'll never know. How to get past this: The moment you hear "If you want to mark your attendance and go" or  "Do whatever you want in my lecture. I don't mind." STOP. Never get up and go. Because he is unpredictable. Don't be surprised if he gets vindictive later.