After the localized and culturally specific character of Book V and its discussion of rites, Book VI, Part A, returns to more conventional philosophical ground. Specifically, it deals with the question of human nature. Part A begins with another Chinese philosopher of the period, Kao Tzu, using an analogy to demonstrate a point about our natures. He says, “To make morality out of human nature is like making cups and bowls out of the willow” (122). In other words, human nature is neither essentially moral nor immoral but can be fashioned, like the willow is into various products, into either.

Mencius responds by using the analogy against Kao Tzu. He says that in Kao’s example the willow tree is mutilated by fashioning it into cups and bowls. Similarly, human nature must be mutilated to be made moral. Consequently, morality cannot prevail if man is amoral and morality is accomplished only by this means. In the next section, presumably because the first exchange was inconclusive, Kao Tzu provides another analogy to discuss human nature. This time it is with whirling water. Kao says that just as water will follow the outlet or channel, to east or west, that has been dug for it, human nature will not necessarily become either good or bad.