The reason most often sited was the recognition that eggs worked as binding (thickening) agents. The food historians to not venture into this territory.Possibly it was a discovery based on trial and error.Creation myths commonly describe how the universe was hatched from an egg, often laid by some mythical water bird swimming in the primordial waters...Early mythmakers viewed both the sun and the egg as the source of all life; the round, yellow yolk even symbolized the sun. In Europe of pagan and Christian times, eggs symbolized life and resurrection.Many foods and cooking methods (leavened bread, roasted meats, yogurt) were "invented" this way. Nobles and priests were particularly well served, with at least forty different kinds of bread and pastries, some raised, some flat, some round, some conical, some plaited.There were some varieties made with honey, others with milk, still others with eggs." ---Food in History, Reay Tannahill [Three Rivers Press: New York] 1988 (p.499-508) ---includes extensive bibliography for further study; use the index to locate information on other types of eggs "Because eggs embody the essence of life, people from ancient times to the modern day have surrounded them with magical beliefs, endowing them with the power not only to create life but to prophesy the future.Eggs symbolize birth and are believed to ensure fertility.
However, the very few ancient Greek recipes to mention eggs date from after the time of Pericles, when the chicken was introduced to Africa.
Other eggs consumed by various ethnic groups include those from plovers, partridges, gulls, turkeys, pelicans, ducks, and geese.
Turtle eggs have been highly prized, and in starvation situations, any eggs, even those of alligators, have been relied upon." ---Cambridge World History of Food, Kenneth F.
It took some times for the habit of using eggs in cooking to catch on.
We do hear of thagomata, made from egg whites, and various stuffings using egg yolks.
Beaten eggs were used as a thickening and to bind sauces and ragouts; hardboiled eggs became an ingredient of various dishes, sometimes with cheese, but here is no evidence that eggs were eaten just as they were, as a dish in themselves.