The chicken or the egg causality ilemma arises from the expression "which came first, the chicken or the egg?" Chickens hatch from eggs, but eggs are laid by chickens, making it difficult to say which originally gave rise to the other. To ancient philosophers, the question about the first chicken or egg also evoked the questions of how life and the universe in general began. Cultural references to the chicken and egg intend to point out the futility of identifying the first case of a circular cause and consequence.