In this Mishnah, we'll talk about a socher (somebody who rents an animal). A socher would be obligated to pay for damage caused by negligence, because he was negligent in watching or caring for the animal, or for a type of damage that he had the ability to prevent. But if there was unavoidable damage, the socher would not be responsible. Here we'll talk about a renter who doesn't keep to the terms of the rental: he's obligated to pay for any damages that happen.
The Mishnah says: Somebody rents a donkey and agrees that he's only going to have it walk on a mountain, but instead he walks it through a valley. Or he says he's going to walk it through a valley, but instead he takes it to a mountain. Even if the distance of the journey he was taking with the donkey—let's say he was having it carry merchandise for him—was 10 mil (a traditional unit of distance) in both cases, whether he went through the valley or through the mountains, he didn't add any distance by going through one of these different areas that he hadn't specified he was going to. He specifically had a deal with the owner of the donkey that he was going to go through the valley or the mountain, and he deviated from that plan. Then we say: the donkey died, and we don't know why. The renter is obligated to pay for it. It could be that the owner specifically wanted his animal to go through a certain type of land, either a mountain or a valley, because the air in those places is different: the air in the mountains is cool, and the air in the valley is warm. Maybe the donkey was used to a certain type of air while it was working and carrying merchandise. The owner of the donkey could claim, “Ah, it died because the renter did not follow the instructions,” and therefore the renter would be obligated to pay.
Now we'll talk about a situation: Is an owner responsible for providing a renter with a replacement animal if the animal he rented is not functioning and can't be used? Let's say somebody rented a donkey, and that donkey became blind. It's sagi nahor over here—beautiful, a positive way of speaking; hibrika means it became, it lit up, but it really became blind. Or it was seized by the king for government service, and it was taken, but it's going to be returned eventually. The owner of the donkey could say, “The animal is yours before you; you have the ability to use it to some extent,” so the owner does not have to replace it. If the donkey is blind, it can still be used in some way. Let's say the man could put merchandise onto it and lead it, even if it's blind. And the king's men are eventually going to return the donkey, so the renter will have it for some time. Therefore, the owner does not have to replace it. But if the donkey died, or it broke—for example, a limb broke—and therefore it can't do any work at all, the owner has to provide another donkey for the term of the rental, or return the money.
We said earlier in the Mishnah that if the renter did not follow the specific instructions about where he could take the chamor (donkey), then he would be responsible for payment if the animal died. But here we'll say that that's only if the animal died for an unknown reason. If there was a specific reason for how the animal died, then the situation changes. HaSocher et ha-chamor (somebody rented a donkey): he agreed to the owner's stipulation that he was only going to take it on a mountain, but he took it to a valley instead. If the donkey slipped and died, the renter would be exempt from payment. The reason is that even though he didn't follow the owner's instructions, you can't consider the animal's death to be the renter's fault. A mountain—a mountain—is steeper. A mountain is more slippery. If he had followed the owner's instructions and gone there, the animal would have been more likely to slip because of the steepness of the mountain. But here, when we're talking about a valley, he took it against the owner's will, but the valley is still not a slippery place. Therefore, the type of death that happened was, in a way, an unavoidable circumstance, an accident, and the renter would be exempt.
But if the animal overheated because of the heat of the valley and then died, the renter would be obligated to pay. He would be responsible for the animal's death. He had an agreement that he was only going to take it on the mountain. The mountain has much cooler air. So when he brought it into the valley and it died of heat, that would be his responsibility because he increased the danger to the animal. And we reverse the situation. Let's say he rented a donkey and agreed that he was only going to take it into the valley, but then he took it to the mountain. If it slipped on the mountain and died, the renter would be obligated to pay for it. If he had kept to his agreement and taken it only to a valley, which is less steep and less dangerous, then maybe the animal wouldn't have slipped. But if the animal died of overheating on the mountain, then the renter would be exempt. He wouldn't be responsible for the death, because if he had taken it to the valley as he agreed, it would have been much more likely to overheat and die. If it died in the harim (mountains) with cool air, it would have died in the valley, which is much hotter.
But if the donkey became overheated and died because of climbing the mountain, the renter would still be obligated to pay because of the exertion he put onto the animal. If he had taken it to the valley, the animal would have been walking downward rather than upward; walking upward was what caused the animal's death. So in that situation, even though it overheated in the mountains, it was because of the exertion, and therefore the renter would be obligated to pay.