1. The Mishnah discusses which sealants one may not use to seal a doorway.
2. There is a dispute about when it is permitted to use such an item to seal a doorway when the item drags on the ground.
3. One may not use a board that is not on a hinge to seal a breach in a wall.
4. Rebbi Yehoshua ben Chananyah explained to a Tzeduki the meaning of the verse, "Their good ones are like thorns."
5. The Mishnah discusses the law of an item used to lock a door that could also be used for crushing peppers.
A BIT MORE
1. A board (or other item, such as a large mat) that serves as a door to an entranceway but does not fit exactly, may not be used if it drags on the ground, because it appears like the Melachah of building.
2. Abaye: It is permitted when it is attached to a hinge. Rava: It is permitted even if it had once been attached to a hinge in this place.
3. This also gives the appearance of building.
4. This means that just as thorns protect open areas, righteous Jews protect Bnei Yisrael.
5. Rebbi Eliezer: It is forbidden to use it to lock the door unless it is tied to the door. Rebbi Yosi: It is permitted to use it to lock the door because it is a vessel.