The chicken or the egg is a reference to the causality dilemma which arises from the expression ``which came first, the chicken or the egg?''. When used in reference to difficult problems, a chicken and egg problem is similar to a Catch 22 situation where
something cannot happen until a second thing does, and the second thing cannot happen until the first does. For example, you cannot find a job without work experience, but you cannot get work experience without first having a job.
The earliest reference to the dilemma is found in Plutarch's Moralia, in the books titled ``Table Talk,'' in a series of arguments based on questions posed in a symposium. Under the section entitled, ``Whether the hen or the egg came first,'' the discussion
is introduced in such a way as to suggest that the origin of the dilemma was even older:
``...the problem about the egg and the hen, which of them came first, was dragged into our talk, a difficult problem which gives investigators much trouble. And Sulla my comrade said that with a small problem, as with a tool, we were rocking loose a great and heavy one, that of the creation of the world...'' Various answers
have been formulated in response to the question, many of them humorous.