What you're asking is where did the phrase "black as a whistle" come from? The Generation of Five Zangs in Huangdi Neijing. The man as black as an altar came from the formation of the five zang in the Yellow Emperor. The original sentence is the Qi of Five Zangs: Therefore, those who see the color as grass die, those who see the yellow as bitter orange die, those who see the black as altar die, those who see the red as blood die, and those who see the white as dead bones die. Black is the color of face and limbs skin as black as coal ash. This term is used to describe the dirty color of the kidney, which can also be seen in other symptoms, such as kidney failure, decreased stomach qi, kidney deficiency, dull complexion, black eyes, black body or senile plaque.