Avodah Zara 47: Exceptions to Houses, Walls, Rocks Which Were Once Idolatrous

Some brief notes on today's daf:

• the rabbis wonder whether we can use a shinuy, an unusual manner of performing an otherwise forbidden task, to permit the offspring of an animal that might be disqualified from use in the mikdash (due to rules around idolatry)
• the rabbis question whether something can be used by Jews if a Gentile worshipped it
• bowing to a date tree; can we use it to make a lulav?
• worshipping an animal; can we use its wool to make holy clothing?
• praying to a stream; can we use its water?

A new mishna teaches that we cannot rebuild a house if its wall is adjacent to a house of idolatry. Instead, the house should be rebuilt four amos into the person's property.  If the wall is owned jointly with the house of idolatry, half of it counts toward the four amos.  Its stones and earth are considered to be tainted, similar to rules of ritual purity.  The Gemara teaches that one might use that space to be filled with idol worship; urination at night.  We then learn that modest people should urinate in the same place both morning and night and it should be away from people.  

• A second new mishna teaches that there are three halachot of houses that are forbidden due to idolatry:
• if the house was intended to be built for idolatry from the start
• if one plastered or illustrated the walls for the sake of idolatry - in this case, the house is permitted after the addition is removed
• if idolatry was brought in and removed, the house is permitted

The Gemara notes that if one bows to a house, Rav forbids that house.  He believed that something was dented and later attached is considered to be detached regarding idolatry.  The rabbis ask about a house that was not built to be worshipped but was worshipped.

A mishna stated that there are three halachot of rocks forbidden due to idolatry:

• if a rock was quarried to be a base for idolatry and the rock will be worshipped, it is forbidden
• if one plastered or illustrated it for the sake of idolatry, when the addition is removed the rock is permitted
• if idolatry was put on and removed, the rock is permitted

The Gemara suggests that the rock should be chiseled with reference to idolatry to be forbidden.   The rabbis argue about whether or not the illustration or plaster might seep into the walls.  They suggest that the plaster or ink could enter the wall through cracks between the bricks.  Rabbi Ami taught that even those rocks could be used once the design is removed.