The Eddie and Dee Sit edition, an audio series of the Talmud Bavli, presents a discussion on Gemara Menachot Daf Nun Dalet. Today's learning is dedicated in the merit of Moshe ben Luna. We begin our study on Nun Gimmel Amud Bet, starting six lines from the bottom of the page. The last words on the line quote the Mishnah: "Rabbi Meir says, 'You take the sourdough from within the mixture and leaven it.'" This discussion centers on menachot that have become chametz.
It is important to note that simply leaving flour to become chametz on its own is insufficient. To create chametz, one must actively introduce a leavening agent, specifically yeast, referred to in the Mishnah as se'or. Rabbi Meir asserts that one should take from the shiur of the isaron itself, which is the specified amount of flour in the mincha. By taking from the isaron, one can create the sourdough and incorporate it into the mixture, effectively leavening it.
In contrast, Rabbi Yehuda argues that this method is not optimal, stating that one should bring sourdough from elsewhere. Rabbi Meir counters this by expressing concern that doing so would distort the shiur. The Gemara then raises the question: "Will it be chaseira (less than the shiur) or yeteira (more than the shiur)?" Rabbi Chisda explains that the outcome depends on the consistency of the sourdough. If it is thick (ava), it will take up more space, potentially resulting in more than an isaron when added to the mixture. Conversely, if the sourdough is thin, it will take up less space, leading to a total that could be less than an isaron.
The Gemara expresses confusion over these details, stating that ultimately, the keli is full, filled to the top with a combination of dry flour and sourdough. Thus, the question remains: how can there be any concern over chaseira or yeteira? Abaye and Rav Yosef clarify that the measurement must be based on the original dry flour, and any addition of sourdough will affect the shiur of flour. They explain that if the sourdough occupies a small volume, it would allow for more flour to fit than if it were dry, thus altering the shiur of the isaron.
Rabbi Meir's approach emphasizes creating the sourdough from within the mixture to avoid affecting the shiur. However, Rabbi Yehuda believes this method results in poor leavening. The Gemara suggests a compromise: take a small amount from the isaron and prepare the sourdough separately, ensuring that it is still considered part of the original isaron. Yet, this raises concerns that people might mistakenly think the sourdough was sourced from outside the isaron, leading to a potential violation of the shiur.
Rabbi Yehuda maintains that the critical factor is the fullness of the keli. As long as it is filled to the isaron, it suffices, regardless of whether the shiur of dry flour is met. The Gemara continues to explore additional cases, discussing the use of apple juice as a leavening agent. The consensus is that apple juice can indeed create chametz, but Rabbi Chananya ben Gamliel argues against its use in menachot due to its potential to create inferior chametz.
The discussion transitions to the principles governing tumah and taharah, particularly in cases where meat swells or shrinks. The Gemara emphasizes that measurements of shiur must be based on the current state of the item, whether it has expanded or contracted. The dialogue illustrates a complex interplay of halachic principles, where the original state and current state of an item can influence its status.
Ultimately, the Gemara concludes that the principles of shiur are contingent upon the current condition of the item, yet exceptions exist for specific cases, such as grogrot, which can be reverted to their original state. This nuanced understanding of halachic measurements and distinctions underlines the importance of precision in determining tumah and taharah statuses, as well as the proper preparation of menachot.