Nathanael West said this quote

...let us consider the holes in our own bodies and into what these congenital wounds open. Under the skin of man is a wondrous jungle where veins like lush tropical growths hang along over-ripe organs and weed-like entrails writhe in squirming tangles of red and yellow. In this jungle, flitting from rock-gray lungs to golden intestines, from liver to lights and back to liver again, lives a bird called the soul.