We are now beginning Tractate Bava Basra. As mentioned, Tractate Nezikin was originally one tractate of thirty chapters, which was divided into three equal parts of ten chapters each. Bava Basra is the third and final part, and therefore we are, in a sense, continuing from the point where we left off at the end of Bava Metzia.
Topics of the Tractate - A Review of the Chapters:
The central topic of Bava Basra is monetary laws, and primarily real estate. These are the topics of the chapters:
Chapter One - The laws applying to the division of property, whether between partners or neighbors.
Chapter Two - The restrictions regarding causing damage to a neighbor's property.
Chapter Three - The laws of chazakah, generally dealing with disputes over property ownership. The well-known rule is "hamotzi mechavero alav hara'ayah" - the burden of proof is on the one who extracts from his fellow: one who seeks to extract an object from the hands of another bears the burden of proof, and the muchzak - the one physically holding the object - is entitled to keep it in his possession unless the other brings convincing proof. However, with land the law is different, and there are other rules defining who is the muchzak and who has the status quo, entitling him to keep the property in his hands without proof.
Chapter Four - The laws of property sales and how they operate.
Chapters Five and Six - A continuation of the laws of sales, including the sale of land and movable property.
Chapter Seven - A return to the laws of property sales.
Chapters Eight and Nine - The laws of inheritance.
Chapter Ten - The laws of halachic documents and contracts, concluding the entire tractate as well as the broader picture of the Order of Nezikin.
Mishnah 1 - The Right to Privacy:
The first chapter deals with division, and the topic of Mishnah 1 is privacy. A person has a right to privacy; his home is intended to grant him two fundamental things: security and privacy. In the time of the Sages, a significant portion of work was done outside the home, in a shared area in front of the houses called the courtyard. Therefore, a person may tell his neighbor that he feels uncomfortable, and request that a partition be built to separate them so that the other cannot observe his actions. In Mishnah 5, we will discuss a neighbor's ability to compel his fellow to participate in building such a wall.
The Mishnah opens: "Hashutafin sheratzu la'asos mechitzah bechatzer" - partners who wished to make a partition in a courtyard. Two neighbors who are partners in a courtyard and request to divide it - and this refers to a courtyard that is not particularly large. Had the courtyard been large enough so that each of the neighbors would receive an area of at least four by four amos in which he could cook and prepare his necessities, each neighbor could have compelled his fellow to actually make a partition. But when the shared area is smaller than eight by four amos, it is too small to divide, unless both parties agreed. Our Mishnah states "ratzu" - wished - meaning they agreed to divide, and therefore they build together.
The Mishnah's wording "la'asos mechitzah" - to make a partition - is not interpreted here as a partition in its regular sense. The meaning of the word here is division - to divide the courtyard into two equal halves, so that each one gains the desired privacy. A halachic partition needs only to be ten handbreadths high, approximately waist height, but such a height does not grant privacy. The wall discussed in our Mishnah is not a halachic partition, but rather a wall separating the two halves at a height of four amos - the height of an average person, so that people's eyes are below the top of the wall, and in this way each neighbor gains the privacy he requested.
Once the two neighbors agreed to divide their small courtyard with a wall in the middle - "bonin es hakosel ba'emtza" - they build the wall in the middle. The halachah is that they are obligated to build the wall in the middle, meaning that both neighbors participate equally in its construction: both in the material costs and in allocating the land. Each one gives half of the land area required to build the wall.
This is the law even if the frontage of one neighbor's property is twice as large as his fellow's. Even if before the division the apartment of one was double in size, and seemingly his use of the front was double - for example, two entrances going out to the courtyard compared to one entrance for his neighbor - it does not matter. From the moment they divided, and since both derive equal benefit from the privacy the wall grants, they must bear its cost and allocate its place equally, half and half, and not in proportion to their degree of use of the rest of the courtyard.
"Makom shenahagu livnos gevil, gazis, kefisin, levenim - bonin" - a place where it is customary to build with rough stone, hewn stone, half-bricks, or whole bricks, they build:
If the custom is to build with a certain building material, a neighbor can compel his fellow to build according to the local custom. The Mishnah lists four materials, and the fundamental rule is that the higher the construction quality, the less space is required, and less is subtracted from the area of the small courtyard:
"Gevil" - Unhewn stones placed on top of one another. Their edges are rough and therefore they require a lot of space: a width of six tefachim.
"Gazis" - Hewn stones, whose edges are smoother and can be placed closer together: five tefachim.
"Kefisin" - Half-bricks, similar to blocks: four tefachim.
"Leveinim" - Whole bricks: only three tefachim.
And if you ask: How is it possible that a whole brick needs only three tefachim, while two halves require four? The answer is that with two half-bricks, mortar is needed to join them together, and the mortar also takes up a tefach.
Therefore, the Mishnah concludes: "Hakol keminhag hamedinah" - Everything follows the prevailing custom. If the accepted custom is not to build a wall at all, but rather to make a picket fence, or even a reed fence made of palm branches and the like - that is all that can be forced upon the neighbor.
Dividing the space according to the types of materials:
"Begevil - zeh nosein sheloshah tefachim vezeh nosein sheloshah tefachim" - Each of the two neighbors provides three tefachim, making a total of six.
"Begazis - zeh nosein tefachayim umechtza vezeh nosein tefachayim umechtza" - The stones are hewn and their edges are smooth, and each provides two and a half tefachim.
"Bekefisin - zeh nosein tefachayim vezeh nosein tefachayim" - With half-bricks, each provides two tefachim.
"Beleveinim - zeh nosein tefach umechtza vezeh nosein tefach umechtza" - Each provides a tefach and a half, making a total of three.
And from here: "Lefichach im nafal hakosel - hamakom veha'avanim shel sheneihem". Since this is the rule, that each one provides half of the materials and half of the space, if the wall falls and they come to rebuild it, they know that the space upon which it stood was allocated equally between them, and the stones as well - when they come to divide the rubble - are divided half and half between the two partners.
The novel point here is rooted in the rule mentioned in the introduction: Generally, when a person is physically in possession of an object such as a brick, the law is "hamotzi mechaveiro alav hara'ayah" (the burden of proof is on the one who seeks to exact something from his fellow), and the other will not be able to get his bricks back without proof - and consequently he has no proof as to what belongs to whom. However, since the rule is that the two neighbors must allocate the space and bear the costs equally, half and half, beis din says that it can, as it were, testify to this - what is known in the terminology of Chazal as "anan sahadi" (we are witnesses) - and therefore half the bricks belong to the neighbor, even if they are all lying in the courtyard of one of them.
In summary: In this section, we discussed the place of Bava Basra as the third part of tractate Nezikin and the order of the topics of its ten chapters, and we learned Mishnah 1, which deals with the right to privacy: Partners who agreed to divide their courtyard build the wall in the middle, and share equally in the land and the cost, even if the frontage of one is double. We also discussed the four building materials and their widths, the rule of "hakol keminhag hamedinah", and the law that if the wall falls - the space and the stones belong to both of them, by virtue of "anan sahadi" that the division was done half and half.