Derek Philby: Mr. Monk, you had a question.
Adrian Monk: If you wouldn't mind.
Derek Philby: That's what teachers do satisfy curiosity.
Adrian Monk: Did you know Beth Landow was pregnant when she died?
Derek Philby: No. No, I didn't, but that would explain why she jumped, wouldn't it? The baby's father, whoever he was, must have run out on her, huh?
Adrian Monk: You. You were the father.
Derek Philby: Unfortunately, you can't prove that, Mr. Monk. Her body's already been cremated.
Adrian Monk: What did she do, threaten to tell your wife? You would have lost everything your new job, family...
Derek Philby: Again, impossible to prove. I think you're failing this course, Mr. Monk.
Adrian Monk: I think I'm doing all right. I have a motive now.
Derek Philby: Well, you're gonna have to do a little better than that, Mr. Monk, because you're in a science classroom now, and when you're in my classroom, if you have a theory, you'd better have some proof to back it up. I was proctoring the S.A.T. test when that poor girl died. I never left the room. Okay? If that mouse vanished, you could think that the snake did it. I mean, he's got motive. He's hungry; he likes to eat mice... But he's in a separate cage. There's no way that the snake could have done it. It is one of the immutable laws of physics, Mr. Monk, nothing can be in two places at the same time. Any thoughts?
Adrian Monk: I think the snake did it.