Kelim, Chapter Nine, Mishnah Six
1) If olive peat or grape skins had been prepared in conditions of cleanness, and unclean persons trod upon them and afterwards liquids emerged from them, they remain clean, since they had originally been prepared in conditions of cleanness.
2) If a spindle hook was sunk into the spindle, or the iron point into the ox goad, or a ring into a brick, and all these were clean, and then they were brought into a tent in which was a corpse, they become unclean.
3) If a zav caused them to move they become unclean.
4) If they then fell into the air-space of a clean oven, they cause it to be unclean.
5) If a loaf of terumah came in contact with them, it remains clean.
Section one: The olives and grapes were squeezed or tread upon by people who were in a state of purity. Then unclean people tread upon the waste productsthe olive peat or the grape skins and then liquids emerged. Generally, liquids make things susceptible to impurity. But because the person treading upon the olive peat or grape skins did not intend to squeeze out the liquids (because he probably wanted them to remain dry), this type of liquid does not make the olive peat or grape skins susceptible to impurity. They both remain pure, and if they are put into an oven, the oven also remains pure.
Section two: The instruments in this section consist of one metal instrument sunk into another larger instrument that cannot become impure because it does not have a receptacle. If the larger item with the smaller instrument inside it are taken into a tent in which a corpse is found, the sunken metal instrument is not protected by the larger item from becoming impure. Metal instruments are not protected from impurity unless they were swallowed by a living being (animal or human).
Section three: A zav (person with abnormal genital discharge) who moves something causes it to be impure, even without touching it. Again, the outer vessel does not protect these instruments from becoming impure.
Section four: Just as they are not protected from being defiled, so too they can defile an oven if they enter its airspace.
Section five: However, if a loaf of terumah bread comes into contact with them, it remains pure because it did not directly come into contact with the spindle hook, iron point or ring. It only touched the spindle, goad or brick and they were pure.