Wally: Are these user specifications complete? I ask because any later changes will cause me to miss the deadline. Man: What if I only need a tiny change later? Wally: I'm counting on it. That way I can blame you when I miss the deadline. Man: How do most people handle this situation? Wally: Well, the pessimists know they're doomed, so it's no surprise to them when it happens. Man: What do the optimists do? Wally: They become pessimists.