At 12 a.m., someone placed a box of nougat chocolate bars in the beis medrash for the talmidim who had stayed learning late. Moshe was on a diet, but took one for his chevrusa, David, who had gone back to his dorm room for a few minutes to get a sefer.
While he was standing by the box, Moshe got into a halachic discussion with one of his friends. He put the chocolate bar down on the table next to the box. Meanwhile, Aryeh came by. He looked in the box, but it was already empty. He saw the bar lying next to the box and took it.
Moshe noticed him taking it. “I’m sorry,” he said to Aryeh. “I already took that bar for my chevrusa, David.”
Aryeh looked at him skeptically. “I’m not sure it was fair to take for him when there weren’t enough for the people who are here now,” he said. He put the chocolate bar down.
“David is also entitled, since he is also learning,” Moshe replied. “He’ll be back in a few minutes. Anyway, I’m on a diet and didn’t take one for myself, so I don’t see any problem taking for him.”
Moshe finished talking to his friend and returned to his place. David returned a few minutes later.
“They put out nougat chocolate bars for the bachurim while you were gone,” Moshe said to him. “I took one for you.”
“Thank you very much,” said David. “However, I’m allergic to nuts, so I can’t eat it.”
“So you don’t want it?” asked Moshe.
“No,” said David. “You can give it to someone else.”
Zvi, who was sitting nearby overheard them. “I didn’t get one,” he said. “The box was finished when I went. Can I have it?”
“Sure,” said David. He reached over and passed the chocolate bar to Zvi.
“Actually, Aryeh had wanted that bar,” Moshe commented. “He even picked it up, but I told him I had taken it for you. Maybe he should get it?”
“Oh, I didn’t realize,” said David. “But I already gave it to Zvi. It’s his now.”
“I’m not sure,” said Moshe. “If you don’t want the bar, then maybe Aryeh has first rights.”
“Rabbi Dayan is still learning here,” said David. “Let’s ask him.”
Moshe, David, Aryeh and Zvi went over to Rabbi Dayan. Moshe related the story to Rabbi Dayan. “Who does the chocolate bar belong to?” he asked. “Aryeh or Zvi?”
“In your case, the chocolate bar belongs to Aryeh,” Rabbi Dayan ruled. “Since David did not want the chocolate, it remained available for anyone to take and Aryeh’s acquisition is valid retroactively.”
“Can you explain more?” asked Aryeh.
“When the box of chocolate was put out,” explained Rabbi Dayan, “Moshe was able to acquire a bar on behalf of David based on the principle of zachin l’adam shelo b’fanav – it is possible to acquire on behalf of someone even when he is not present.” (C.M. and Shach 269:1)
“So the chocolate bar should belong to David?” asked Zvi.
“It would be David’s if he were interested in getting the chocolate,” said Rabbi Dayan. “However, you cannot force someone to accept something he does not want. If the recipient expresses disinterest in the item and says he does not want it, the acquisition on his behalf is null and void retroactively. Thus, when Aryeh initially picked up the chocolate bar, it actually was available, so that he acquired it.” (C.M. 243:1)
“What if Aryeh hadn’t picked it up?” asked Moshe. “Let’s say he had just asked me about it while it was sitting on the table.”
“Then it would remain hefker and available to whoever takes it now,” replied Rabbi Dayan. “It would then belong to Zvi, who has it now.”
“What about a slightly different case,” said Moshe. “Let’s say the box was not left out as hefker, but someone had given me the chocolate bar for David and he didn’t want it. Could I then keep it for myself?”
“In that case, where you accepted a gift from someone on behalf of David and he didn’t want it,” replied Rabbi Dayan, “you should return it to the giver. He did not make it available to everyone, only to the intended recipient. If he doesn’t want it, it remains property of the giver.” (C.M. 245:10; Pischei Choshen, Kinyanim 15:27)