Adelbert von Chamisso

This man, although he appeared so humble and embarrassed in his air and manners, and passed so unheeded, had inspired me with such a feeling of horror by the unearthly paleness of his countenance, from which I could not avert my eyes, that I was unable longer to endure it.

I will give you three days to seek your shadow. Return to me in the course of that time with a well-fitted shadow, and you shall receive a hearty welcome; otherwise, on the fourth day - remember, on the fourth day - my daughter becomes the wife of another.

By irreducibly complex I mean a single system composed of several well-matched, interacting parts that contribute to the basic function, wherein the removal of any one of the parts causes the system to effectively cease functioning.