Moed Katan, Chapter One, Mishnah Five
The first section of this mishnah deals with a priest inspecting leprous symptoms on a person. Leprosy (or some other similar type of skin disease) is dealt with in Leviticus 13.
The second part of the mishnah deals with certain acts of mourning during the festival. It is brought here because the first of those acts involves digging, which is generally forbidden on the festival because it is laborious.
1) Rabbi Meir says: [Priests] may inspect leprous symptoms at the outset [during the festival] for [the priest to make] a lenient assessment, but not to make a strict one.
a) But the sages say: neither for a lenient nor for a severe assessment.
2) Furthermore Rabbi Meir said: a man may gather his fathers and mothers bones, since this is a joy for him.
a) Rabbi Yose says: it is mourning for him.
3) A man should not stir up wailing for his dead, nor hold a lamentation for him thirty days before the festival.
Section one: According to Rabbi Meir a priest may inspect a person to decide whether his symptoms make him impure, but only if he is going to pronounce the person pure. The mishnah does not want anything to damper the celebration of the festival, and pronouncing him impure will only distress him. It seems that if the priest sees that the person is impure, he is not supposed to say anything at all. The mishnah allows this even at the outset, meaning at the initial stage of the process, when the infected person is going from a state of purity to impure. The priest may also examine him later on when the infected person is already impure, as long as he will declare him to be pure.
The sages think that once the priest goes to examine the symptoms and sees that the person has tzaraat (the skin-disease) he must declare the person impure. He cannot remain silent. Rabbi Meirs halakhah is therefore untenable. The sages however agree that we should avoid a situation where a person might be declared impure on the festival. Therefore, they instruct the priest not to even examine the symptoms in the first place. Better to avoid the problem altogether than to be put in the situation where he would have to remain silent in the face of impurity.
What is fascinating about this section is how the notion of impurity is treated. It is as if impurity doesnt even exist unless the priest declares it impure. In other words, the priests declaration is what makes something impure, not its actual physicality. Both Rabbi Meir and the sages seem completely unbothered by the fact that a person might really have this disease and yet not be declared impure.
Section two: In mishnaic times they would first bury the body until the flesh had decomposed. About a year later they would gather the bones and put them into a more permanent place, called in English an ossuary. In our mishnah two rabbis debate whether the gathering of bones is a joyous or a sad occasion. According to Rabbi Meir, bringing ones parents bones to their final resting place is a joyous occasion. Therefore, it is permitted during the festival. Rabbi Yose says that collecting the bones is part of the mourning process, since it will remind him of the painful loss of his parents. Therefore, he may not collect the bones during this week.
Section three: When it comes to other mourning practices, even Rabbi Meir agrees that he may not do so during the festival. This mishnah does not deal with a person who died during or right before the festival, a topic which shall be covered in chapter three. Rather, the mishnah refers to a person who tells a professional eulogizer to recite a public eulogy for someone who died a long time before the festival, or to someone who himself recites a eulogy for someone close to him who died a long time before the festival. Reciting eulogies for one who died a while before the festival should not be done even within the thirty days preceding the festival because the memory of the powerful eulogy will stay with those who hear it for thirty days, dampening their ability to celebrate on the festival.