Commentary for Bava Kamma 2:2

How is the tooth accustomed to eat what is appropriate for it... What that it says in what matters is this said returns upon what that it said it eats fruits or vegetables, but eating garments or vessels in the public domain obligates in half damages since it is the way of people to place garments or vessels in the public domain for when they are needed. And the explanation of what that it benefits, that he pays for items which are appropriate for its portion of eating from things it's normal for the animal to eat, for example, a donkey that ate 10 liters of dates, the master pays for the donkey the value of 10 liters of barley. And if it was the price of barley was more he pays the value of the dates alone, and like this is the way to evaluate and judge. And when it was placed in the midst of the market and turned to the side and ate, then he pays what he damaged.

כיצד השן מועדת – in what manner is it “forewarned?” And it answers: to eat what is is appropriate for it.

How is the tooth [of a beast] an attested danger to eat that which it is fit to consume? A beast is an attested danger to eat fruit and vegetables. [If however] it ate clothing or utensils [the owner] pays only half damages.
When does this apply? [This applies] in the domain of the damaged party But if it was within the public domain, the owner is not liable.
If [the beast] benefited, [the owner] pays what it benefited.
How does [the owner] pay what [the animal] benefited? [If it ate] from the middle of the marketplace, [the owner] pays what [the animal] benefited. [If it ate] from the sides of the marketplace, [the owner] pays for the damage [the animal] did. [If it ate] from in front of the store [the owner] pays for what [the animal] benefited. [If it ate] from inside the store [the owner] pays for the damage [the animal] did.
The previous mishnah taught us the laws dealing with damages done by an animal’s “regel” leg through walking (trampling). This mishnah teaches damages done by an animal’s “shen” or tooth. Note that the mishnah does not deal with vicious biting by an animal but with an animal that damages by eating. The laws in this mishnah are related to Exodus 22:4 which speaks of a crop-destroying beast. Our mishnah will deal with several issues: 1) what does an animal eat, thereby causing its owner to become liable; 2) differences in liability based on where the animal eats; 3) two different levels of liability, a greater level in which the owner is obligated to pay the actual cost of damages, and a lesser level in which the owner pays that which the animal actually benefited.
There are really three parts to the mishnah. The first section tells us that an owner is only liable when an animal eats things that an animal normally eats. For instance, if my dog goes into your house and eats your cupcakes, I am liable. However, if he eats your mail, I am liable only for half damages.
The second section deals with where the damages are done. I am liable when my animal goes onto your property to damage. I am not liable if you carelessly leave your things in the public domain and my animal eats them. However, the end of the mishnah returns and refines this clause. If you leave things on the side of the public domain, that is not considered careless and the owner of the damaging animal would be liable.
Finally, in sections three and four we introduce a new type of payment, compensation for that which the animal benefited and not for the damage done. For instance if you leave an expensive cut of steak in the public domain and my animal eats it the damages may be 100 dollars. However, since I would not feed my animal steak, rather I would usually feed her cheap dog food, I am only obligated for the amount of dog food that I will now not have to feed her, since she already ate. Paying for the benefit is usually much less that the actual damages.
You should note the highly formulaic nature of this mishnah. It teaches many laws but uses few words. (This is especially true in the Hebrew. In the English I have added words to make the mishnah read better). The mishnah repeats the same structures and phrases over and over again, as does the previous mishnah. Remember, this is oral law, recited and memorized orally. Having repeated structures and few words makes the mishnah much easier to remember and repeat.
Questions for further thought:
 What is the difference between in front of the store and in the store? From this mishnah, can you imagine how their stores were set up?
 What might the law be if I did regularly feed my dog expensive steak?
 What might the law be if my dog is accustomed to eating shoes, and he goes onto your property and eats your shoes?

משלם חצי נזק – for it is unusual (to eat clothing or chew up utensils).

בד"א וכו' - it refers to when it eats fruits or vegetables that are in the public domain, it is exempt, for we require (Exodus 22:4): “When a man lets his livestock loose to graze in another’s land,” but if it ate clothing or utensils, even in the public domain it is liable one-half damages, for people generally put clothing and utensils in the public domain according to the hour and it is the “horn” in the domain of the person suffering damages and he is liable.

משלם מה שנהנית – these are not valid payments but rather if it ate something that its value was great, we view it as if they barley, and he doesn’t pay anything other than the value of the barley at its cheapest, which is a full third less than what they are sold for in the marketplace. But, if it ate something whose worth is less than the barley, he pays the worthy of that thing that it ate at its cheapest, and if it (i.e., the animal) ate that which he damaged such as that it ate the wheat but since it did not benefit, it [the owner] is exempt [from payment].

מצדד הרחבה משלם מה שהזיקה – if it (i.e., the animal) stood and at the sides of the road in a place where it is not the manner of bulls to walk there, it is not compared to the public domain, and it pays what it damages.