metaphor. He even jokingly replaced "Tradition" with "Competition" and sang it aloud. In the opening sequence, you see Tevye delivering milk. He's sloshing it around and loses quite a bit to the ground. The story is about change being inevitable and what matters is how you deal with change. Well, if a competitor milk man pops up and he has a way to deliver milk without losing any, then he's probably going to do a lot better than Tevye. So Tevye would have to adapt to survive. They say that you shouldn't cry over spilled milk, but that makes the assumption that your competitors are also spilling milk. I probably didn't convey my point very well. But all it takes is for one firm in the market to adopt a more efficient way of doing things for the entire market to change. You adapt or you die.