The phrase "near Zhu Zhechi is black, near Mexico is black" comes from Mencius "so we should not dye it carelessly". This idiom means: approaching cinnabar will turn red; It turns black near the ink. Metaphor is easy to make people better by being close to good people; Getting close to bad people often makes people bad. In a word, this idiom warns people to choose people carefully, because environment and interpersonal relationship have great influence on people.