- The exemption of מבריח ארי מנכסי חבירו vs. an animal falling into someone’s garden
The Mishnah on Daf 55b taught that if a sheep fell into someone’s garden, damaging the produce, the owner pays for its benefit, but not the full damages (since its fall was an accident). Rav says: בנחבטה – the case is where it was struck by falling onto the produce, cushioning the animal’s fall. The Gemara explains that Rav means that he pays not only the animal’s benefit from eating produce, but he even pays the benefit of the produce softening its fall. One might have exempted the owner, because it is tantamount to מבריח ארי מנכסי חבירו – chasing a lion away from someone’s property, where he does not collect benefits from the property’s owner, because he was performing a mitzvah in protecting the property. Two reasons are offered why the exemption of מבריח ארי does not apply here: (1) מבריח ארי is done מדעתו – knowingly, whereas האי לאו מדעתו – this [owner of the garden] saved the animal from injury unknowingly. (2) מבריח ארי does not suffer a loss by chasing away the lion, האי אית ליה פסידא – this [one] suffers a loss of his produce’s damage, and therefore may collect the animal’s benefit.
- If the owner is liable מערוגה לערוגה, or יצתה לדעת
It was taught above that if someone’s animal fell into a garden and ate produce, he pays for its benefit, but not the full damages. Rav Kahana says this is only true for that bed onto which it fell (Rashi explains the animal could not restrain itself from consuming that bed), אבל מערוגה לערוגה – but if it went from one bed to another and ate there, משלמת מה שהזיקה – he pays for what it damaged, because the owner is negligent for not removing it. Rebbe Yochanan says that even if the animal went from one bed to another all day, the owner would still only pay its benefit, עד שתצא ותחזור לדעת – until it leaves the garden and returns with the owner’s knowledge. Rav Pappa clarifies that once it leaves with the owner’s knowledge, he is liable for its damages even if it returned without his knowledge (and ordinary lesser guarding does not exempt him), because the gardener’s owner can say to him: כיון דילפא – once it has learned to enjoy my garden’s produce, כל אימת דמשתמטא להתם רהטא – whenever it escapes it will run there and requires a greater guarding to prevent it from returning.
- שמין על גב שדה אחר
The Mishnah on Daf 55b taught that where an animal damaged produce in a field, the damage is not assessed according to the value of the produce, but according to the field’s loss in value. Furthermore, the assessment is not made for the specific area of damage, but as part of a greater area of a beis se’ah of land. Rav Masna provides the source: "ובער בשדה אחר" – and it consumes in the field of another, מלמד ששמין על גב שדה אחר – this teaches that they assess the damage based on another (larger) field. The Gemara asks how the price of a beis se’ah is evaluated. Rebbe Yose bar Chanina says it is evaluated based on a sale of sixty beis se’ah (divided by sixty). Rebbe Yannai says it is based on the value of a tarkav (half-se’ah) in a sale of sixty beis tarkav (i.e., thirty beis se’ah), which is then doubled. Chizkiyah holds we do not evaluate a beis se’ah at all, and only evaluate the area of land damaged as part of an area sixty times its size. Later, Rava says this leniency only applies to an animal’s damages, but a man’s damages are assessed directly on the amount damaged, not a ratio of one to sixty.