Kelim, Chapter One, Mishnah Four
This is the last mishnah that ranks defiling agents. It ends with the greatest source of impuritythe dead body.
1) Above the zav is the zavah, for she conveys impurity to the man who has intercourse with her.
2) Above the zavah is the metzora, for he conveys impurity by entering into a house.
3) Above the metzora is a [human] bone the size of a barley grain, for it conveys impurity for seven days.
4) More strict than all these is a corpse, for it conveys impurity by ohel (tent) whereby all the others convey no impurity.
Section one: The zavah conveys impurity to the man who has relations with her, just as does the menstruant. In other words, not only is he impure, but he also defiles that which he lies upon, even without contact.
Section two: When a metzora enters a house, everything in the house is impure, even if he doesn’t come into contact with it.
Section three: Contact with a bone from a dead body makes a person impure for seven full days.
Section four: This is the final clause of the hierarchy. The most severe form of impurity is conveyed by a dead body, for it conveys a significant form of impurity to anyone found in the same “ohel” as the body. In rabbinic parlance, “ohel” doesn’t just mean “tent” as it does in Hebrew. It means “overhanging.” We shall learn more details concerning this concept throughout the tractate, and also in tractate Ohalot (I bet you can’t wait!).