אמר רב הונא אמר רב ביצה עם יציאתה נגמרה מאי עם יציאתה נגמרה אילימא עם יציאתה נגמרה ומותרת לאכלה בחלב הא במעי אמה אסורה לאכלה בחלב והתניא השוחט את התרנגולת ומצא בא ביצים גמורות מותרות לאכלן בחלב
Rav Huna said that Rav said: An egg is fully formed upon its emergence; i.e., it is not considered an egg until it is laid. The Gemara inquires: What is the meaning of the statement: An egg is fully formed upon its emergence? To which issue is Rava referring? If we say he meant an egg is fully formed and called an egg only upon its emergence, and at this stage it is permitted to eat it with milk, this indicates that while an egg is still inside its mother, even if it is fully formed, it is considered meat and it is prohibited to eat it with milk. But isn’t it taught in a baraita: With regard to one who slaughters a chicken and finds fully formed eggs inside it, it is permitted to eat them with milk?
אלא עם יציאתה נגמרה ומגדלת אפרוחים במעי אמה אינה מגדלת אפרוחים למאי נפקא מינה למקח וממכר כי ההוא דאמר להו ביעי
.... Rather, Rav certainly did not prohibit an egg that has not yet been laid. Instead, his statement should be explained as follows: An egg is fully formed upon its emergence, and it produces chicks, i.e., an egg laid in the regular manner can be incubated and a chick will hatch from it. By contrast, an egg that remained inside its mother cannot produce chicks. The Gemara asks: What is the practical halakhic difference of this observation? The Gemara answers: It is relevant for buying and selling. In other words, the difference between the types of eggs has ramifications for terms of commerce. This is like that incident involving a certain individual who would say to the general public: Eggs
דפחיא למאן יהבו ליה ביעי דשחוטה אתא לקמיה דרבי אמי אמר להו מקח טעות הוא והדר
of a live chicken, who has? He sought to purchase eggs of this kind. They gave him eggs of a slaughtered chicken. He came before Rabbi Ami, claiming he had been cheated. Rabbi Ami said to the sellers: This is a mistaken transaction, and it is rescinded; the sale is void.
פשיטא מהו דתימא האי לאכילה קא בעי להו והאי דקאמר דפחיא משום דצריבן למאי נפקא מינה למיתבה ליה ביני ביני קמ"ל
The Gemara asks: It is obvious that the transaction is void, as he specified exactly what he wanted. The Gemara answers: The ruling is necessary, lest you say that this individual wants them for food rather than for chicks, and that which he said, that he is looking for eggs of a live chicken, he said only because they are hard-shelled, mature eggs. What is the practical difference,i.e., what is this man claiming from the seller according to this rejected interpretation? He is merely demanding to refund him the difference in value between the two types of eggs. Rabbi Ami therefore teaches us that the sale involved a fundamental error, as the eggs of a slaughtered chicken are unfit for incubation. The transaction is therefore void.
ומבואר על פי דברי ספר שער משפט (סי' רל"ג סק"א) שהובאו בגידולי שמואל בסוגייתנו, שרב פה לשיטתו במסכתות בבא קמא דף מו ע"א; ובבא בתרא דף צב ע"א שהולכין בממון אחר הרוב. ואילו הלכה כשמואל שאין הולכין.
