Bava Metzia 9: Acquisition of an Animal and What it Carries; Using a Migo to Understand Acquisition

Amud (a) concerns itself with the acquisition of a found animal.  The rabbis discuss some of the overlapping implications of pulling an animal, sitting on an animal, holding an animal's reins, and squeezing or directing an animal with one's legs. They also consider the usual ways that animals are acquired in different regions.  If two people find this animal simultaneously, how is the animal divided?  Usually pulling and driving are forms of acquisition, but sitting on an animal and holding an animal's reins are not.  How is acquisition of an animal determined in such a situation?

One of our notes teaches that acquisition is permitted on Shabbat, though it is not encouraged.  

Amud (b) turns us toward the question of what is included in one's acquisition.  If a person pulls an animal, does s/he acquire the vessels that are sitting on that animal?  Would a person who wanted the vessels but not the animal acquire those vessels by pulling the animal?  Is the animal like a 'mobile courtyard' in this case, and thus what is left in the courtyard is acquired by its owner?  

The rabbis then consider whether a boat is like a mobile courtyard whereby a fish that jumps into the boat is automatically acquired by the boat's owner.  Rava suggests that a boat is not like a mobile courtyard because it sits idle while the water moves it.  What about a woman whose husband throws a get into her basket as she walks by?  Is the basket like a mobile courtyard? Regardless, the rabbis agree that she is moving while the basket is with her, and thus she is divorced when the get falls into her basket.

A new Mishna teaches that if a person is riding an animal and spots a found item on the ground, he can tell another person to pick it up for him.  If that person picks up the item and says, "I have acquired this", then it belongs to him.  However, if he picks up the item and hands it to the rider and then says, "I acquired that because I picked it up first," then it is as if he has said nothing.

The Gemara compares this Mishna to a debate in Pe'a.  In Pe'a (4:9), we learn that a person who gleans the corners of his field might wish to give that produce to a specific poor person.  However, rabbis question whether a rich person is able to designate pe'a for a particular poor person and not just for the first poor person who finds it.  

The conversation continues, wondering whether a rich person might be permitted to designate his field's pe'a for a poor person.  In this case, the principle of migo is used: if a poor person is permitted to acquire food for himself, all the more so should he be able to acquire food for another poor person.  However, a wealthy person cannot save pe'a for a poor person, because that would require two amigos, which is not permitted:

• First migo: Since a rich person can denounce ownership of his field and become poor, he will then be permitted to acquire food for himself.
• Second migo: If he can acquire food for himself, all the more so can he acquire food for another poor person.