As we mentioned in the previous mishnah, the fourth chapter of Maseches Taharos establishes that found utensils are presumed tamei, and we must assume they are impure. Jerusalem, however, is an exception to this rule, and that is the subject of our mishnah.
The View of Rabbi Meir:
The mishnah distinguishes between two locations: "Kol hakeilim hanimtza'im biYerushalayim derech yeridah l'veis hatevilah - temei'in, derech aliyah - tehorin" - all utensils found in Jerusalem along the path leading down to the immersion house are tamei, and those found along the path going up are tahor. The basis for the distinction lies in the principle that "shelo k'derech yeridasan aliyasan" - their ascent was not by the same route as their descent. The immersion house had one entrance passage descending to the mikvah and a separate exit passage, and people did not leave by the same way they entered. The reason: they did not want the tamei and the tahor people leaving through the same area, lest they come into contact with one another.
Utensils found along the path of descent: in the place where those who are tamei go down to the mikvah, we must assume the utensils are tamei, even in Jerusalem.
Utensils found along the path of ascent: in the area where people exit the mikvah, the utensils are tahor, since the context itself demonstrates that they came from the tahor people ascending from their immersion.
The View of Rabbi Yose:
Rabbi Yose says "kulan tehorin" - they are all tahor, even those found along the path leading down to the mikvah. The reason: the Sages did not decree impurity on doubtful utensils in Jerusalem. Even though we are dealing with a utensil whose origin is unknown, and it is not known whether it is tamei or tahor, they did not make a decree about it. This, then, is a special halachah in Jerusalem: even though the utensil's status is in doubt, it is tahor, even along the path of descent.
The Utensils That Are the Exception:
According to Rabbi Yose everything is tahor, "chutz min hasal v'hamagreifah v'hamaritzah hameyuchadin lakevaros" - except for the basket, the shovel and the pickaxe that are designated for graves:
The sal: a particular type of basket.
The magreifah: a kind of rake or shovel.
The maritzah: an iron tool with a very sharp point, used for breaking apart stones for burial purposes.
The reason these utensils are considered tamei is that we are speaking of versions of these tools that are designated and designed from the outset for work in cemeteries and burial areas. For that reason they can be presumed tamei even in Jerusalem.
In summary: In this mishnah we learned that Jerusalem is an exception to the presumption that found utensils are tamei. According to Rabbi Meir, those found along the path leading down to the immersion house are tamei and those found along the path going up are tahor, since the route of descent and the route of ascent were separate from one another so that the tamei and the tahor would not mix. According to Rabbi Yose they are all tahor, since the Sages did not decree impurity on doubtful utensils in Jerusalem, except for the basket, the shovel and the pickaxe, which by their very manufacture are designated for work with graves.