" With these words Schiller acknowledges the equal rights of sensuousness and spirituality. He concedes to sensation the right to its own existence. But at the same time we can see in this passage the outlines of a still deeper thought: the idea of a “reciprocity” between the two instincts, a community of interest, or, in modern language, a symbiosis in which the waste products of the one would be the food supply of the other. "

― C.G. Jung , Psychological Types