The ironic nature of human experience
There is an idea offered by way of irony. Perhaps humans think about mythology backwards. Instead of viewing stories as the product of human life, Barthes suggests the relationship is actually the other way. Stories aren't the product of human life, they literally constitute the entire experience a human has with their reality.
The biological irony of myth
Only humans make mythologies for humans, right? That is ironic, because it means that human biology is the true origin for human myths, because after all, human brains invent myths from their own psychologies, and if the myth translates well to another person's experience of reality, perhaps that myth gets powerful. The organic nature of myth is ironic, given the consistency of mythological devices and systems.
The ironic zeitgeist
Even in nations where it is fashionable to defy one's culture, the counter-culture is already implied in the zeitgeist. The zeitgeist is ironic because it is the product of public human experience, shared experience, and shared beliefs or assumptions, but it is doubly ironic because it also informs those things by helping a person clarify their identity as that person relates to the culture of their time.
The irony of masculinity and femininity
The ironic balance between seemingly opposite forces comes up with respect to human gender roles. The irony is that in public wrestling, a sport that wears bravado and masculinity on its face, masculinity is actually the crisis of the myth, leading to Barthes's ironic conclusion that the purpose of the wrestling mythology is to help offer a construct or game where people can psychologically work through the relationship between not feeling masculine enough and potentially becoming violent.
The irony of myth and science
Well, certainly the mythologies of human culture don't extend into science do they? Barthes says they do, because the human imagination is the device they use to solve mathematical and scientific principles, so there is an ironic mythology that governs science and mathematics. The difference is that in science, the agreement is clearly to reject former narratives once more accurate systems of thought are discovered. He mentions Einstein for this point.