It is as we learned in a mishna (Shabbat 73a): One who carries out an item from one domain to another domain is liable. The Gemara claims: Are we not also dealing with a case where he is bringing it in from a public domain to a private domain, and nevertheless the mishna refers to it as carrying out?

The Gemara questions this assertion: But perhaps the mishna is dealing with a case of carrying out an item from a private domain to a public domain. The Gemara defends its claim: If so, let it instead teach: One who carries out an item from a private domain to a public domain is liable. What is the reason it used the more generalized formulation: From one domain to another domain? To teach that one is liable even if one transfers an item from a public domain to a private domain.

The Gemara explains further: Even though the mishna addresses carrying an item in from a public domain to a private domain, it refers to it as carrying out. The Gemara explains: What is the reason for this? The tanna refers to any act that involves removal of an item from its place as carrying out. Accordingly, the term can appropriately be used even when an item is brought in to a private domain from a public domain.

Ravina said: The language of the mishna in tractate Shabbat is also precise in indicating this, as it teaches: With regard to acts of carrying out [yetziyyot] that are prohibited on Shabbat, there are primarily two basic actions that are four cases from the perspective of a person inside a private domain, and two basic actions that are four cases from the perspective of a person outside, in a public domain. And then, immediately, in the continuation of that mishna, it explicates the cases of bringing in an item. Conclude from it that the term: Carrying out, is also used to refer to bringing in an item.

Rava said: One cannot make any inference from the language of the mishna, as it is not referring to acts of carrying out. Rather, it teaches domains. In other words, it means: With regard to the domains of Shabbat there are two types, the existence of which leads to four types of prohibited transfers, two with regard to carrying out and two with regard to bringing in.

§ The mishna teaches: With regard to different shades of leprous marks, there are two types that are actually four. We learned in a mishna there (Nega’im 1:1): With regard to different shades of leprous marks, there are two types that are actually four: The baheret, mentioned in the Torah (see Leviticus 13:2), is considered a primary mark; it is an intense white, like snow. Secondary to it, i.e., a sub-category of it, is a mark that is white like the lime plaster of the Sanctuary walls.

That mishna continues: The se’et mentioned in the Torah is considered a primary mark; it is like white wool. Secondary to it is a mark that is white like the membrane of an egg. The ordering of different shades is relevant in determining which shades can be combined together. In order for a leprous mark to be halakhically significant, it must at least be the size of a split Cilician bean [geris]. If a mark is that size, but it is composed of different shades of white, none of which is alone the size of a geris, then if the different shades are compatible they can combine together and will thereby render the person ritually impure.

Rabbi Ḥanina said: Who is the tanna who taught this mishna, which delineates the different shades of leprous marks into two groups? It is not in accordance with the opinion of Rabbi Akiva. As if it were in accordance with the opinion of Rabbi Akiva one would be presented with a difficulty: Since with regard to which shades can combine together, Rabbi Akiva says: The different shades should be ordered this one above this one, and that one above that one, i.e., according to their degrees of brightness, from the most bright to the darkest shade, as follows: Snow white, i.e., baheret; wool white, i.e., se’et; lime; and egg membrane; and only two adjacent shades can combine together. But if so, you have rendered pure a mark that is white like the lime plaster of the Sanctuary walls and is smaller than a geris, as it cannot be combined with any other shade of white.

The Gemara explains: With which other shade could we combine the lime-colored mark? We cannot say: Let us combine it together with a snow-white baheret, which is the primary mark relative to a lime-colored mark, as there is a wool-white se’et, which is a more bright white than a lime-colored mark but less bright than snow white. Since baheret is not adjacent to lime it cannot combine with it. We cannot say: Let us combine it together with a se’et, as a lime-colored mark is not its secondary mark and a primary mark can combine only with its secondary mark. This is difficult because the mishna’s categorization of a lime-colored mark as a secondary mark indicates that it can be combined with another shade of white. Perforce, the mishna is not in accordance with the opinion of Rabbi Akiva.

The Gemara asks: If that is so, that Rabbi Akiva holds that only adjacent shades of white can combine together, why didn’t Rabbi Ḥanina also bring proof from a mark that is white like the membrane of an egg, as with which other shade could we combine it? We cannot say: Let us combine it together with a wool-white se’et, which is the primary mark relative to an egg membrane–colored mark, as there is a lime-colored mark, which is a more bright white than an egg membrane–colored mark but less bright that wool white. Since se’et is not adjacent to egg membrane it cannot combine with it. We cannot say: Let us combine it together with a lime-colored mark, as it is not its type, i.e., they are not of the same category, and so they cannot combine.