But when I started thinking about the lecture and thinking about just preparing it and tweaking it, and again I had last thought about it back in December-- and you know, when you make a syilabus for a course you think about the course, you outline it, you think it's all going to go well, and then you get halfway through the course and sometimes different things seem exciting to you or you suddenly get a gut feeling that: 'wow, I was going to have a really abstract discussion today, and I don't want to have an abstract discussion. 