What does Wan Wen mean by "one red, two black, three white and four yellow"?
Literary play "one red, two black, three white and four yellow" is actually a taboo in the literary play world, that is, these varieties cannot be touched.
One red, two black, three white and four yellow refers to the river top red, two black refers to rhinoceros horn, three white refers to ivory, and four yellow refers to the oriental raw materials of golden bell and cypress.