Question

“Come to the zoo on Chol Hamo’ed!” said all
the adverts. Yehoshua decided to take the opportunity to see the wonders of
Hashem‘s creation. He walked in through the main gate, thinking that
entry was free on Chol Hamo’ed. When he was looking at the lions, he
felt a tap on his shoulder. "Your ticket, please," said the official. "I
thought entry was free today," he said. "I’ll leave now if you wish," he
offered. The official would not be satisfied with less than the full entry
fee. Yehoshua was only prepared to pay for visiting that part of the zoo
which he had actually seen. Who is right?

Answer

Reuven owns a field, surrounded on all four sides by
Shimon’s fields. Shimon erects fences on three sides of Reuven’s field.
Reuven erects his own fence on the fourth side. He is now obligated to pay
his share in the construction of the other three fences. By completing the
fencing-in of his field he has shown that he was pleased with his neighbour’s
work on his behalf. In Tractate Bovo Kamo (20b), our Sages deduce from
this statement that if it was Shimon who had completed the fencing-in, he
could not demand Reuven’s participation in the construction costs. When one
person does work for himself and another person automatically derives benefit
from it, the beneficiary is not obligated to pay for the benefit he enjoyed (zeh
neheneh v’zeh lo chosser pottur). This presents Tosafos
with a difficulty. Surely the three fences which Shimon built were also
constructed for his own benefit. The fact that they also enclosed Reuven’s
field did not increase his costs. If so, why does Reuven have to pay his
share of the construction costs if he completed the fourth side? Tosafos
answers that the fact of Reuven completing the fourth side at his own expense
indicates that he is pleased that a fence has been erected and that he is
prepared to pay for this benefit. He must therefore participate in the cost
of the other three fences. This answer requires clarification. What has
Tosafos added? At the end of the day, Shimon has not incurred any extra
expense because he had to enclose Reuven’s field as well. If so, what right
does he have to demand payment for this automatic benefit?

Rav Tzvi Spitz (Mishptei Hatorah, Bovo Kamo, No.34)
suggests the following explanation. The fact that Reuven indicates that he is
prepared to pay for the work Shimon performed on his behalf retroactively
converts him into Reuven’s employed worker from the outset. We now view the
fence construction performed by Shimon as having been for two people, himself
and his neighbor. Even though it never entered Shimon’s mind that he was
working for Reuven, since Reuven’s actions are interpreted to be appointing
Shimon as his paid worker, he is obligated to pay him for his work. However,
Tosafos add that if a person automatically benefits from another’s
work and indicates that the only reason why he wishes to enjoy this benefit
is because it is free of charge, he cannot be forced to pay for it since
zeh neheneh v’zeh lo chosser pottur.

Let us return to our case. Yehoshua had no intention to
avoid paying for visiting the zoo. He just thought that this benefit was
available free of charge on Chol Hamo’ed. Had he known that such a
visit would cost him money, he would have been prepared to forego this
enjoyment. The fact that there was one additional visitor in the zoo did not
cause the zoo authorities any additional expense. We can therefore conclude
that this is a further case of zeh neheneh v’zeh lo chosser pottur.
According to the halochoh, if Yehoshua now leaves the zoo, he cannot
be made to pay for his partial tour. However, should he decide to see the
rest of the animals, he would have to pay the full entrance fee.