Chapter 2, Mishna 1
Abaye asked Rabba, what if a courtyard opens directly into an enclosure around a well in the public domain – may we carry from one to the other? What if two courtyards open into such an enclosure? Answer depends on whether those courtyards are already joined by an eruv – a proper eruv. We don’t want people think the the corner posts around the well create that eruv. What if the well runs dry? What if the well runs dry, and then it starts running again? Depends on a related question: may we carry within an enclosure made of partitions erected on Shabbos?