This tractate winds up with the most interesting conundrum. What happens if the paroches (the curtain in holy Temple which separates the holy of holies from the hall with the menorah, lechem hapanim and gold altar) becomes impure due to coming into contact with something impure. This is an eye opener. How can this happen in the most holy temple? There is tremendous care by a host of workers, priests, assistants in keeping the people, animals, and utensils free of impure contamination (tumah). Anyone who goes to see the archeological digs around the temple sees many mikvaos. We know there are several mikvoas in the temple complex. We know people took great pains to stay pure to bring sacrifices. So how does this happen. How can the curtain become impure? How can a person who had touched a sheretez or nevilah or some spritz of a dead animal come into contact with the curtain?
The SD would like to propose why it happens is not that important. The issue is that it can happen. The central lesson is that MISTAKES can happen. Anyone or any environment can is susceptible to error. Random things happen that we have no control over.
The Talmud is recognizing that no one is perfect. The most controlled environment in the world is still subject to imperfection. What is important is how we deal with mistakes. That is the beauty of the Talmud. The next tractate is Yoma- Yom Kippur or the day we deal with our mistakes.