Kelim, Chapter One, Mishnah Five
There are ten grades of impurity when it comes to impurities that are a result of emissions from a male body. These include semen, flux (abnormal genital discharge), skin disease (tsaraat) and separated limbs.
There are ten [grades of] impurity that emanate from a person:
1) A person before the offering of his obligatory sacrifices is forbidden to eat holy things but permitted to eat terumah and [second] tithe.
2) If he is a tevul yom he is forbidden to eat holy things and terumah but permitted to eat [second] tithe.
3) If he emitted semen he is forbidden to eat any of the three.
4) If he had intercourse with a menstruant he defiles the bottom [bedding] upon which he lies as he does the top [bedding].
5) If he is a zav who has seen two discharges he conveys impurity to that on which he lies or sits and is required to undergo immersion in running water, but he is exempt from the sacrifice.
6) If he saw three discharges he must bring the sacrifice.
7) If he is a metzora that was only enclosed he conveys impurity by entry [into an ohel] but is exempt from loosening his hair, from rending his clothes, from shaving and from the birds offering.
8) But if he was a confirmed metzora, he is liable for all these.
9) If a limb on which there was not the proper quantity of flesh was severed from a person, it conveys impurity by contact and by carriage but not by ohel.
10) But if it has the proper quantity of flesh it conveys impurity by contact, by carriage and by ohel.
a) A “proper quantity of flesh” is such as is capable of healing.
b) Rabbi Judah says: if in one place it has flesh sufficient to surround it with [the thickness of] a thread of the woof it is capable of healing.
Section one: The lowest level of impurity is a person who has immersed in the mikveh but is not fully pure until he brings his sacrifices. An example is the metzora (see Keritot 2:1). Such a person cannot eat sacrifices, but he can already eat terumah and second tithe.
Section two: A tevul yom is a person who has immersed in the mikveh but is waiting for the sun to set before he becomes fully pure. He can’t eat terumah or sacrifices, but he can still eat second tithe.
Section three: A man who has a seminal emission (and has not yet been to the mikveh) cannot eat any of these three things, giving him a more serious form of impurity than the tevul yom.
Section four: A man who has intercourse with a menstruant has an even more serious form of impurity. This was explained above in mishnah three.
Section five: A zav who has had one or two abnormal discharges has a higher form of impurity, in that he needs to immerse in a spring in order to become pure. See Leviticus 15:13, “When one with a discharge becomes clean of his discharge, he shall count off seven days for his cleansing, wash his clothes and bathe his body in fresh water; then he shall be clean.”
Section six: If he has three abnormal discharges within three days, he must bring a sacrifice of either two turtle-doves or two pigeons. See Leviticus 15:14.
Section seven: There are two stages when it comes to the impurity of a person who has developed tzaraat (skin disease). The first is when the priest sends him away to wait and see if fuller signs of the affliction develop. Already at this period he conveys impurity by entering a house (see mishnah four). However, he does not have to rend his clothes, loosen his hair or shave his body. Concerning these things see Leviticus 13:45. He also does not need to bring sacrifices, if later he is determined not to have tzaraat.
Section eight: Once it is determined that he does have tzaraat, he is liable to do all of these things.
Section nine: A limb which is severed from a living person conveys impurity, even if the person remains alive. If it does not have a sufficient amount of flesh, then its level of impurity is such that it defiles by contact and carrying, but not by entering into an ohel. Below the mishnah will explain “sufficient amount of flesh.”
Section ten: If there is a sufficient amount of flesh, then it also conveys impurity by being in an ohel.
For there to be “a sufficient amount of flesh” there must be enough flesh on the limb such that it could heal if it was attached to the body. So if one’s finger falls off, for instance, but it had already been damaged so much that there was barely any flesh on it, it doesn’t convey impurity by being in an ohel.
Rabbi Judah provides a slightly different interpretation. If there is enough flesh in one place on the limb, such that if it was stripped off it could surround the limb, and the strip would have the width of the thread of a woof, then it is sufficient.