Kelim, Chapter Seventeen, Mishnah Eight
1) The olive of which they spokeit is one that is neither big nor small but of moderate sizethe egori.
2) The barleycorn of which they spokeit is one that is neither big nor small but of moderate sizethe midbarit
3) The lentil of which they spokeit is one that is neither big nor small but of moderate size–the egyptian kind.
4) “Any movable object conveys uncleanness if it is of the thickness of an ox goad”it is one that is neither big nor small but of moderate size.
a) What is meant by “one of moderate size?” One whose circumference is just a handbreadth.
Section one: Many halakhic measures are based on the olive, including many minimum measures of how much food a person needs to eat to fulfill a mitzvah. This olive is of medium size. This medium-sized olive even had a namethe egori oliv.
Section two: The barleycorn is the size that a piece of a bone needs to be to convey impurity. This barleycorn is of medium size and it is called “midbarit,” which means wild.
Section three: For a piece of a dead creepy crawly thing (a sheretz) to convey impurity it needs to be the size of a medium lentil, of the Egyptian kind.
Section four: This halakhah is taken from Ohalot 16:1 (a tractate which we have not yet learned). An “ohel” or tent is anything that overhangs. If a dead body or piece thereof is found under an ohel and under the same ohel there is a pure vessel, the dead body defiles the pure vessel. Here we learn that if the ohel is a movable object, it must be the thickness of a medium-sized ox goad. Its circumference must be at least one handbreadth for it to convey uncleanness.