Sukkah 36B

ותו לא מידי.

The Talmud notes: And there is nothing more to discuss here. Clearly, the opinions of R' Akiva and R' Shimon do not necessarily coincide.

גדלו בדפוס ועשאו כמין בריה אחרת ⁠— פסול. אמר רבא: לא שנו אלא כמין בריה אחרת, אבל כברייתו ⁠— כשר. פשיטא! כמין בריה אחרת (תנן)! לא צריכא, דעבידא דפי דפי.

The baraita continues: If he grew the etrog in a mold and shaped it to appear like a different species, it is unfit. Rava said: A baraita states that it is unfit only if he shaped it to appear like a different species; however, if he shaped the etrog so it still appears like its own species, it is fit. The Talmud asks: That is obvious; the phrase: Like a different species, is explicitly taught in the baraita. If it shaped like its own species, it is fit. The Talmud answers: No, Rava’s statement is necessary to deem fit an etrog that is shaped into the shape of many planks, i.e., pieces of wood attached to each other. Although its shape is not precisely that of a regular etrog, it sufficiently resembles a regular etrog and is fit.

איתמר אתרוג שנקבוהו עכברים, אמר רב: אין זה הדר. איני? והא רבי חנינא מטביל בה ונפיק בה! ולרבי חנינא קשיא מתניתין!

§ It was stated that the amora’im disagree with regard to an etrog that mice pierced. Rav said: That is not beautiful. Is that so? But wouldn’t R' Ḥanina dip his etrog, eat part of it, and fulfill his obligation with what remained of it? The Talmud asks: And for R' Ḥanina, the Mishnah is difficult, as it states that an incomplete etrog is unfit.

בשלמא מתניתין לרבי חנינא לא קשיא: כאן ביום טוב ראשון, כאן ביום טוב שני. אלא לרב קשיא! אמר לך רב: שאני עכברים דמאיסי.

The Talmud explains: Granted, for R' Ḥanina, the Mishnah is not difficult, as it can be explained that here, when the Mishnah prohibits one from using an incomplete etrog, it is referring to performing the mitzva on the 1st day of the festival of Sukkot, when a complete taking of the species is required; and there, when R' Ḥanina’s conduct leads to the conclusion that an incomplete etrog is fit, it is referring to performing the mitzva on the 2nd day of the Festival or after that. However, according to Rav, who said an etrog that was pierced by mice is unfit, R' Ḥanina’s conduct is difficult, as the requirement of beauty applies on all 7 days. The Talmud answers: This is not difficult, as Rav could have said to you: Mice are different, as they are repulsive. When mice pierce an etrog, what remains is antithetical to beauty. When a person bites an etrog, what remains can still be considered beautiful.