The Mishna on our daf discusses whether, when burning hametz just before Pesah, it is necessary to separate food that has been ritually defiled (tameh) from food that is ritually pure (tahor). In this context, Rabbi Hanina Segan ha-Kohanim reports that in the Temple, the kohanim never refrained from burning meat that had been defiled by a low-level tuma together with meat that had become defiled by a higher level tuma. This discussion leads to several pages of discussion in the Gemara on the subject of tuma v’tahara.
Since we are no longer involved in the Temple service, nor do we eat teruma or korbanot, we do not interact with these laws on a regular basis. Nevertheless, these are among the most basic laws that are detailed in the Torah and are developed in the Talmud by the hakhamim. According to the Torah, there are differing levels of things which ritually defile. They are:
Avi Avot ha-tuma (e.g. a dead body)
Avot ha-tuma (e.g. someone who came into contact with a dead body; someone suffering from leprosy)
Rishon le-tuma (things that came into contact with avot ha-tuma)
Under a variety of circumstances, there can be a sheni, shlishi or even revi’i le-tuma, all of which are discussed in the following pages of the Gemara.
Rabbi Hanina Segan ha-Kohanim who records this ruling in the Mishna was one of the tannaim who lived through the destruction of the Second Temple and continued to teach for some time afterwards. According to one tradition, he was one of the Harugei Malkhut killed by governmental decree. As his title indicates, he held an important position as assistant to the Kohen Gadol while the Temple was standing, and he stood in for the Kohen Gadol if he was ill or tameh and could not perform the Temple service.
Most of Rabbi Hanina’s teachings that are recorded in the Mishna refer specifically to the Temple and its laws, i.e. the sacrificial service and the laws of ritual purity – tuma v’tahara.