On daf 17, chapter 2 of massehet Baba Batra, the gemara asks why the mishna starts with bor and ends with kotel. The gemara explains that enables us to learn that the width of a bor wall is 3 tefahim.
I looked in several comments, but I still do not understand this conclusion.
Do you have one ?
Thank you for your help.
Emmanuel, Paris, France
There must be a 6-Tefach material separation between the holes of two pits. Therefore, the two neighbors who want to dig pits in their property should move 3 Tefachim into his own property, away from the boundary (3+3=6), in order to dig his pit.
When the Gemara teaches this Halachah, it seeks to teach another point: that a standard pit needs a 3-Tefach-thick wall in order to be used properly, and if one buys a pit, he is entitled to receive with the "hole" also ownership of a 3-Tefach "wall" surrounding the pit.
Therefore, the Gemara says: Back away 3 Tefachim from your neighbor's pit's wall (instead of saying merely "back away 3 Tefachim"). In this manner, the Gemara teaches that a pit needs a 3-Tefach wall. Since we know that the neighbor also must distance his pit from the boundary by 3 Tefachim, it must be that the wall of a pit is 3 Tefachim.
All the best,
Reuven Weiner