What is Misfortune?

Misfortune. What is happiness, really? The absence of sadness? No, I don't think that's correct.
What is sadness? The absence of happiness? No, I don't think that's correct.
What is darkness? The absence of light?
What is light? The absence of shadow?
What is luck? The absence of misfortune?
What is misfortune? The absence of happiness?

What is human?