Mark (who requests you call him by his first name) is a great man. He realizes that juniors in the major (and seniors who have been abroad) rarely have a clue how to write a 40-ish page paper, and is prepared to guide you along the way. His office hours fill up quickly, but are always encouraging. I left them with an average of half a dozen new ideas scribbled down. Our seminar received emails from him at least once or twice each week, and they were not always seminar-related. He often took the time to encourage us to attend lectures, conferences, dinners, etc. He is probably one of the most approachable professors in the department. I'm not sure what a larger lectures would be like with him-he seems especially well-suited to smaller discussions, but certainly take a class with him when he is back from his sabbatical.