(Gemara - Rav Chisda): If Levi sold to Yehudah something worth five (e.g. Zuz) for six, and its value increased to eight, Yehudah can retract, but Levi cannot, since Yehudah was overcharged;

Yehudah can say 'had you not overcharged me, you could not retract. Now that you overcharged me, can you retract?!'

Support (Mishnah): If Reuven sold good wheat, and it was found to be bad, Shimon can retract.

(Rav Chisda): If Levi sold something worth six for five, and its value decreased to three, Levi can retract, but Yehudah cannot, since Levi was underpaid;

He can say 'had you not underpaid me, you could not retract. Now that you underpaid me, can you retract?!'

Support (Mishnah): If Reuven sold bad wheat, and it was found to be good, Reuven can retract.

Question: What does Rav Chisda teach that we do not know from the Mishnah?

Answer: One might have thought that either can retract in Rav Chisda's case (when the price was too high or low);

The Mishnah is when the price is correct, but the quality was not as stated;

Version #1 (Rashi): When he sold good and it was found to be bad, Reuven cannot retract, because Shimon can say that there was no mistake. "Ra Ra Yomar ha'Koneh" (the buyer always claims that the merchandise is bad, even if he knows that it is not, and likewise, the seller always claims that it is good).

Version #2 (Ri): When he sold good and it was found to be bad, the Mishnah teaches that Shimon can retract;

One might have thought that Reuven can say that there was no mistake, for "Ra Ra..." (you knew that the seller always claims that the merchandise is good, even when it is not).

(Mishnah): He sold Shechamtis (wheat), and it was found to be white...

Inference (Rav Papa): Since it was found to be white, this teaches that (Shechamtis is red (the only other color of wheat. It is called SheCHAMtis, for it looks like the Chamah (sun), i.e.) the sun is red.

Support: The sun appears red in the morning and evening;

It does not appear so the rest of the day because our eyes cannot see so clearly because it is so bright.

Question (Beraisa): "The appearance (of Tzara'as) Amok Min ha'Or" is like the sun appears, deeper than the shade.

Tzara'as appears white!

Answer: It is like the sun appears regarding deepness, but not regarding color (really, the sun is red).

Question: The one who asked the question understood that the sun is white. How did he understand why it appears red in the morning and evening?

Answer: In the morning its rays pass through the roses of Gan Eden; in the evening, its rays pass through the entrance of Gehinom;

Some say, vice-versa.

(Mishnah): If he sold wine, and it was found to be vinegar, either can retract.

Suggestion: Our Mishnah is like Rebbi, and unlike Chachamim.

(Beraisa): Wine and vinegar are the same species;

Rebbi says, they are two species.

Rejection: The Mishnah is even like Chachamim. Chachamim consider them to be one species only regarding Ma'aser and Terumah, like R. Ila'i;

(R. Ila'i): If one separates bad Peros to be Terumah on good Peros, it takes effect - "v'Lo Sis'u Alav Chet ba'Harimechem Es Chelbo";

If it did not take effect, he would not bear sin!

Regarding a sale, all agree that some people prefer wine, and others prefer vinegar.

(Mishnah): If Reuven sold Peros to Shimon (for a price per unit measure) and he (Shimon) did Meshichah but did not measure it, Shimon acquires;

If he measured but did not do Meshichah, he does not acquire;

If Shimon is clever, he will rent the premises (to acquire immediately).

If Shimon buys flax from Reuven, he does not acquire until he moves it from place to place;

If it was attached to the ground and he detached any amount, he acquires.

(Gemara - Rav Asi citing R. Yochanan): If he measured and put it in a Simta (an adjunct to a Reshus ha'Rabim where people are permitted to rest things), he acquires.

Suggestion (R. Zeira): Perhaps you heard that this applies when he measured into his box in the Simta?

Rejection (Rav Asi): That is obvious. R. Yochanan would not need to teach that case!

Question: Did R. Zeira accept this answer?

Answer: We learn from the following:

(R. Yanai (R. Yochanan's Rebbi) citing Rebbi): Partners in a joint Chatzer can acquire one from the other.

Suggestion: They acquire by putting on the ground.

Rejection: No, they acquire by putting in the other's Kli.

Support (R. Yakov citing R. Yochanan): If he measured and put it in a Simta, he did not acquire.

Question: R. Yanai and R. Yochanan (according to Rav Asi) said that he acquires!

Answer: We must say that if he puts it in the other's Kli he acquires, if he puts it on the ground he does not acquire (Rav Asi misunderstood R. Yochanan's teaching).

Question (against Rav Asi - Mishnah): If he measured but did not do Meshichah, he does not acquire.

Suggestion: This is in a Simta.

Answer: No, it is in a Reshus ha'Rabim.

Question (Reisha): If he did Meshichah but did not measure it, Shimon acquires;

Meshichah does not acquire in a Reshus ha'Rabim!

(Abaye and Rava): Mesirah acquires in a Reshus ha'Rabim, or in a Chatzer that does not belong to both of them;

Meshichah acquires in a Simta or in their joint Chatzer;

Hagbahah acquires everywhere.

Answer: The Mishnah means, he acquires by doing Meshichah from the Reshus ha'Rabim to a Simta.

Question (Seifa): If Shimon is clever, he will rent the premises.

No one owns the Reshus ha'Rabim to rent it to Shimon!

Answer: The Mishnah means that if he is in a Reshus ha'Yachid, if Shimon is clever, he will rent the premises.