There is an ancient saying: “Thought initiates not by itself, but because of circumstances.” This is followed by, “Once the circumstances are gone, so is the thought.” We, ordinary beings, revolve according to circumstances. Virtuous circumstances lead to a virtuous mind, and pure circumstances lead to a pure mind. When the circumstances are polluted, our mind will also be impure. This is what is meant by, “One who touches vermillion knows the brightness of red, and one who touches tar knows the dullness of black.”