Ohalot, Chapter Eleven, Mishnah Three
Our mishnah continues to deal with the portico that had a split in it. The mishnah discusses various objects placed below that either do or do not close the split such that impurity on one side can travel to the other.
1) A thick woolen jacket or a thick wooden block does not bring uncleanness until they are one handbreadth high off the ground.
2) If [garments] are folded one above the other they do not bring uncleanness until the uppermost is one handbreadth high off the ground.
3) If a person were placed there [under the split in the portico]:
a) Bet Shammai says: he does not bring the uncleanness.
b) But Bet Hillel says: a person is hollow and his uppermost side brings the uncleanness.
Section one: Despite the fact that these items are one handbreadth thick, they are not considered to be an ohel such that there is an ohel directly beneath the split in the roof of the portico. For something to be an ohel it must also have an empty space.
Section two: If there are a few garments folded one on another, they bring uncleanness when placed underneath the split if the bottom part of the upper garment is at least one handbreadth off the ground. In other words, the entire upper garment must be one handbreadth above the ground in order for it to form an ohel over the other garments. We might have thought that since the presence of the lower garments does not prevent an ohel from being formed, then the lower folds of the upper garment also wouldn’t prevent an ohel from being formed. The mishnah teaches that there is a difference between the lower and upper garments. The lower garments are in the ohel and the upper garment forms the ohel.
Section three: Bet Shammai says that a person’s body cannot be considered an ohel. Bet Hillel looks at a person’s abdomen as being hollow. The upper side is the top of the ohel and therefore a person closes the split in the portico.