|Ask Rabbi Simmons|
The idea that milk, which comes from a fleishich animal, would be dairy, seems easy to understand because of the Torah verse of not seething a kid in its mother's milk. But why are eggs pareve and not fleishich (meat)?
Before we discuss the subject of "eggs" it would first be imperative to understand first why chicken and dairy products are prohibited.
The Talmud says that when the Torah says "do not boil a kid in it's mother's milk," it is only referring to meat from the 3 kosher domesticated animals - cow, goat and sheep.
However, since people "intuitively" associate chicken as "meat," then it became the law as well not to mix chicken and milk. This view was accepted by the entire Jewish people as binding law about 1500 years ago.
The rabbinic prohibition of not eating poultry with dairy products is one of the many "fences around the Torah" that the Sages instituted. As the name "fence" suggests, the prohibition helps protect the Torah from being transgressed accidentally, and help people protect themselves from spiritual damage.
Furthermore, the 6-hour waiting period that applies between eating meat and milk products, likewise applies when one eats chicken.
Now, regarding eggs... Eggs which were not laid and are found inside the chicken attached to the veins of the chicken, are forbidden to be eaten together with milk since they are still in the formation process and therefore considered like part of the chicken meat itself. Hence, the rabbinic prohibition would apply even to the eggs.
If, however, the eggs were laid and are thus completely developed; they are not considered part of the chicken meat. Rather a complete egg is in fact considered an entity by itself and is not considered meat that can be confused with animal meat. Hence there the rabbinic prohibition would not apply here and it would be permissible to eat the egg with dairy products.
(Sources: Code of Jewish Law" Y.D. 87:1; 87:3; see "Shach" and "Taz"; and 87:5; "Pitchei Teshuva" 12 ad loc).
With blessings from Jerusalem,
Rabbi Shraga Simmons