Rav Huna quoted Rav as saying: “An egg is finished when it comes out.” It was suggested that it might mean “once it is laid, it is permitted to be eaten on Yom Tov, but if it is found in the slaughtered body of its mother, it would be forbidden to eat on Yom Tov.”
But this was rejected because it was taught in a Beraisa that completed eggs found inside a slaughtered chicken may be eaten on Yom Tov.
It was further suggested that perhaps Rav holds like our Mishna that even an unborn egg is forbidden on Yom Tov, and this Beraisa argues and permits it. It was pointed out, however, that the Mishna only discusses an egg laid on Yom Tov, but would certainly permit an egg found inside its mother.
Suggestion: Perhaps Beis Hillel [in the Mishna (001)] do forbid an egg found inside the mother, the Mishna discusses the case of a laid egg to let us know that Beis Shammai permits it even then?
Response: But then whose opinion is the Beraisa (023) recording? Beis Shammai would permit the eggs even after they were laid, and Beis Hillel would forbit such eggs.
Resolution: Rav was letting us know that it is only capable of hatching a chick if it has been laid. This is not a halachic matter but it is relevant for commerce [the Chachomim sometimes made statements for usefulness].
There was once someone who walked through the street saying “Who has eggs of a cakling hen?” [a hen cackles when it delivers, this man was looking for eggs that had been laid which would be capable of hatching]. He was given eggs from a slaughtered hen. When the case came before Rav Ami he declared it a mekach ta’us - a deception and voided the sale.
Challenge: Of course it’s a mekach ta’us!
Resolution: You might say that he actually needed the eggs for food but he wanted eggs that had been laid because they’re more complete and taste slightly better. In such a case the sale would not be void, only that the seller would have to pay for the discrepancy in value.
[There are two types of eggs. 1. Eggs of a male - these come when the hen has contact with a rooster. 2. Eggs from the ground - these are secondary eggs which come indirectly when the hen is warmed by burrowing into the ground]. There was a man who was looking for “Eggs from a male”. He was given eggs from the ground. When the case came before Rav Ami he declared it a mekach ta’us - a deception and voided the sale.
Challenge: Of course it’s a mekach ta’us!
Resolution: You might say that he actually needed the eggs for food but he wanted eggs caused by a male because they’re fatter. In such a case the sale would not be void, only that the seller would have to pay for the discrepancy in value.