Rambam - 1 Chapter a Day

Any place designated as a public domain with regard to the Sabbath is also considered as a public domain with regard to the laws of impurity.

The four cubits that are adjacent to the public domain are considered as a public domain with regard to the laws of impurity. Similarly, a karmelit, e.g., the sea or a covered walkway, is considered as a public domain with regard to the laws of impurity.

There are places which, though they are considered as private domains with regard to the Sabbath, are considered as public domains with regard to the laws of impurity. They are the paths leading to storage caverns, cisterns, and wine presses, an enclosed valley in the summer, a basilica of kings, i.e., a building that is very wide with space for the king's carriage drivers to stay; it has many openings to the public domain, and a poren, i.e., a large building with two openings, one opposite the other, and a courtyard to which many people would enter through one opening and depart through the other. Also, the lanes leading to a sea or a river, although they are fenced in from either side, are considered as a public domain with regard to the laws of impurity if people can climb over the fences. Pillars and bathhouses are also placed in this category. Similarly, the entire Temple Courtyard is considered as a public domain with regard to the laws of impurity.

Gardens in a city over which the thoroughfare of a city pass are considered as a public domain with regard to the concept of impurity.

When a garden is guarded, it is a private domain. When it is not protected, it is a public domain with regard to impurity. Similarly, a large basilica, when its gates are opened, is a public domain with regard to impurity. When it is closed, it is a private domain in all aspects.

When a valley is enclosed with a fence, in the winter, it is a private domain with regard to the Sabbath and ritual impurity. If it was not enclosed, it is a private domain with regard to impurity alone. When, however, the winter passed after a valley was fenced in, it is considered as a private domain with regard to impurity even in the summer.

This is what is meant by "the summer": When the grain is harvested from the valley. This is what is meant by "the winter": When the second rain begins. The area between the round barrel of grapes and the pile of grape pomace is considered a public domain with regard to impurity.

With regard to ritual impurity, a vineyard in front of the harvesters is considered as a private domain; the portion behind the harvesters, as a public domain. When does the above apply? When many people enter from one direction and leave from the opposite direction. The law pertaining to other places aside from those which we mentioned is: Just as they are a private domain with regard to the laws of the Sabbath, so too, they are a private domain with regard to the laws of impurity.

There are places that are not considered as a private domain with regard to the Sabbath laws, but are, nevertheless, considered as a private domain with regard to the laws of impurity, because the people do not use them. They are: trees and holes in the walls of the public domain even if they are not four handbreadths by four handbreadths. What is implied? There was a tree standing in the public domain with impurity in it. One climbed to the top of the tree and he is in doubt whether or not he touched the impurity, he is impure because of the doubt. One inserted his hand into a hole in which impurity is situated and he is in doubt whether or not he touched it, he is impure because of the doubt.

When there is a store that is impure which is open to the public domain, and a person is in doubt whether or not he entered, he is pure despite the doubt. For the entire store is considered as the carcass of a creeping animal lying in the public domain in which instance, if a question arose whether one touched it, he is pure. If there are two stores, one pure and one impure, in the public domain, and a person entered one, but he is in doubt whether or not he entered the impure store or the pure store, he is impure because of the doubt. This is considered as a doubt that arose in a private domain, because a store is considered as a private domain. Similarly, if in the winter there is a valley that contains many fields with at least one field known to be impure and one pure, and a person said: "I entered this valley and I do not know if I entered that field or not," he is impure because of the doubt. The rationale is that when a doubt arises in a private domain - even a doubt whether one entered - the person is impure.

When a place was considered a private domain, it then became a public domain, and then it became a private domain, the ruling depends on its immediate status. While it is a private domain, when there is a doubt, the person is impure. While it is a public domain, when there is a doubt, the person is pure.

Entities that are situated in the public domain are considered as the public domain. What is implied? There was a container ten handbreadths high in the public domain in which was situated a source of impurity. If one is in doubt whether he touched the container, he is pure despite the doubt. If he inserted his hand into the container, but he was in doubt whether he touched the impurity, he is impure because of the doubt. If there was a stone container resting on his shoulder and a loaf of bread that was terumah wrapped in tree bast or paper contained within it and there was a doubt whether or not another person touched it, it is impure because of the doubt.

When there is a donkey in the public domain that was ten handbreadths high, impurity was placed on it and a doubt arose whether a person touched the donkey's back, he is pure despite the doubt. If he extended his hand above the donkey and he was in doubt whether or not he touched the impurity, he is impure because of the doubt. Similarly, if there was a rock that was ten handbreadths high placed in the public domain and impurity was placed on it, if there was a doubt whether or not one touched the top of the rock, he is pure despite the doubt. If he climbed on top of the rock, but he was in doubt whether or not he touched the impurity, he is impure because of the doubt.

In all of the following situations: a) a zav was riding on his donkey; another person was riding on another donkey and they were riding on the way and the person was in doubt whether or not he touched the zav; b) an impure child was being carried on his father's shoulder and a pure child was being carried on his father's shoulder, the fathers were walking next to each other and a doubt arose whether one child touched the other; c) a person was carrying a package on his shoulder; there was unidentified saliva stuck to the wall and a doubt arose whether or not it touched it; d) utensils were spread out on a surface more than ten handbreadths high in the public domain; an impure person passed by and a doubt arose whether he moved them or not. In all these instances, the person or the article is pure.

Blessed be God who grants assistance.