MISHNA: There are four primary categories of damage: The category of Ox; and the category of Pit; and the category of Maveh, which, based on a discussion in the Gemara refers either to the tooth of an animal that causes damage or to a person who causes damage; and the category of Fire.

Each of these categories is unique; therefore, the halakhot of one cannot be derived from another. The defining characteristic of the primary category of Ox is not similar to the defining characteristic of the primary category of Maveh, and the defining characteristic of the primary category of Maveh is not similar to the defining characteristic of the primary category of Ox. And the defining characteristics of this category of Ox and that category of Maveh, in which there is a living spirit that causes damage, are not similar to the defining characteristic of the category of Fire, in which there is no living spirit.

The mishna continues: And the defining characteristics of this primary category of Ox and Maveh and that primary category of Fire, in which the typical manner of their components is to proceed from one place to another and cause damage, are not similar to the defining characteristic of the primary category of Pit, in which the typical manner of its components is not to proceed from one place to another and cause damage; rather, it remains in place and the damage is caused by the injured party proceeding and encountering the obstacle.

The common denominator of the components in all of these primary categories is that it is their typical manner to cause damage, and the responsibility for their safeguarding to prevent them from causing damage is incumbent upon you, the owner of the animal or generator of the fire or the pit. And when a component of any of these categories causes damage, the owner or generator of the component that caused the damage is obligated to pay restitution for damage with best-quality land.

GEMARA: From the fact that the mishna teaches its ruling employing the term: Primary categories, by inference, there are subcategories of those primary categories. The Gemara asks: Are their subcategories similar to them, i.e., to their respective primary categories, so that the same halakhot apply to them, or are they dissimilar to them?

The Gemara cites additional areas of halakha where there are primary categories and subcategories and considers the relationship between them: With regard to Shabbat we learned in a mishna (Shabbat 73a): The primary categories of labor prohibited on Shabbat number forty-less-one. There too, from the fact that the mishna teaches its ruling employing the term: Primary categories, by inference, there are also subcategories.

With regard to the primary categories of labor prohibited on Shabbat, their subcategories are similar to them, as it is no different if one unwittingly performed labor that is a primary category, for which he is liable to bring a sin-offering, and it is no different if one unwittingly performed labor that is a subcategory, for which he is liable to bring a sin-offering. Likewise, it is no different if one intentionally performed labor that is a primary category, for which he is liable to be executed by stoning, and it is no different if one intentionally performed labor that is a subcategory, for which he is liable to be executed by stoning.

And what difference is there between a primary category and a subcategory? The Gemara explains: The practical difference is that if one unwittingly performs two labors classified as different primary categories together, during a single lapse of awareness, or, alternatively, if one unwittingly performs two labors classified as subcategories of two different primary categories together, during a single lapse of awareness, one is liable to bring a sin-offering for each and every labor that he performed. Each primary category of labor is an independent transgression. While if one unwittingly performs a labor that is a primary category and another labor classified as its subcategory during a single lapse of awareness, he is liable to bring only one sin-offering.

The Gemara asks: And according to Rabbi Eliezer, who deems one liable to bring two sin-offerings even if one performs a labor classified as a subcategory together with a labor that is its primary category, why is one labor characterized as a primary category and why is the other labor characterized as a subcategory? The Gemara explains: Of the labors prohibited on Shabbat, that which was a significant labor in the Tabernacle, the Sages characterized it as a primary category, and that which was not a significant labor in the Tabernacle, the Sages characterized it as a subcategory. The labors prohibited on Shabbat are derived from the labors employed in the construction of the Tabernacle; therefore, their classification is also based on their significance in its construction.

With regard to ritual impurities, we learned in the mishna (Kelim 1:1): The primary categories of ritual impurity are as follows: Any of the eight species of the creeping animal enumerated in the Torah (Leviticus 11:29–30), and semen,