In this Perek (chapter), we'll talk about different testimony that Rabbi Chanina, who was one of the Sgan HaKohanim, one of the administrators of the Kohanim (priests), testified about. We'll first talk about Tum'ah—impurity—and about causing something to become a higher level of Tum'ah. We'll talk about it in terms of the Terumah (priestly offering) or the Kodashim (sacred offerings) that are already Tameh (impure), the Mishnah says.
Rabbi Chanina, Sgan HaKohanim, who was an officer of the Kohanim, gave testimony about four different matters. Number one: In all the days of the Kohanim, they never refrained from burning Korban (offering) meat that became Tameh by touching a Sheni (second-degree impurity) of Tum'ah. The laws of Tum'ah and Taharah (purity) are beyond the scope of this Mishnah, but if something touches a Sheni of Tum'ah, it becomes a Shelishi (third-degree impurity) in terms of its impurity. So it was a lower level of impurity, and they would burn it together with other Korban meat that became Tameh by touching an Av HaTumah (primary source of impurity). If something touched an Av HaTumah, it's a Rishon (first-degree impurity).
So even though these Korbanot, these different pieces of meat, are now going to be Tameh by touching each other, af al pi shemosifin tum'ah al tumato—even though, by burning two pieces of meat together, you're going to add a greater level of Tum'ah to the Tum'ah of the first piece. The Tum'ah of the first piece was a Shelishi. So now that piece is going to touch a Rishon, and they're going to be burned together. So the Shelishi becomes a Sheni, because it touched the Rishon. So the level of Tum'ah has increased. But Rabbi Chanina says that regardless, even though the level of Tum'ah is going up, the Kohanim who were in charge of the Beit HaMikdash burned these pieces together anyway.
We see from here that even though you're not allowed to cause Tum'ah to Kodashim, once something is already impure and not usable, you're allowed to put a higher level of Tum'ah on it, because it's no longer a situation where it's going to be eaten, but it has to be burned because of the Tum'ah.
The next Tanna (sage) is even more lenient. Hosif Rabbi Akiva, Rabbi Akiva went to the next level. Miyamai, in the days of the Kohanim, says Rabbi Akiva, the Kohanim would not hold back from taking oil of Terumah that became disqualified by having contact with Tum'ah, a Sheni level of Tum'ah, so the oil was now a Shelishi. They wouldn't hold back from taking that oil and putting it in a metal lamp that had become Tameh by touching somebody who became Tameh from a corpse, so the lamp was now an Av HaTumah. Af al pi shemosifin tum'ah al tumato. Even though by doing this, they were adding a greater level of Tum'ah to the oil's previous level of Tum'ah.
After it came into contact with its tevul yom (one who immersed that day), the oil is now considered to be a Shelishi, a third level of Tum'ah. Now that it came into contact with a lamp, which was an Av HaTumah, it becomes a Rishon. So we see from here that even though it's forbidden to cause Tum'ah to Terumah, like we all agree on, it is permissible to make a Rishon out of Terumah that was previously a Shelishi. So in other words, it can go up two levels, according to Rabbi Akiva. The Terumah is being burned anyway, and therefore you can get rid of it no matter what. So therefore, it can go up two levels, according to Rabbi Akiva. So he's even more lenient than Rabbi Chanina. Rabbi Chanina told us that it's permissible to raise the level of Tum'ah one degree by making a Sheni into a Rishon. What Rabbi Akiva is saying is that you're even allowed to raise it two degrees by making a Rishon out of something that was previously a Shelishi, a third degree.