Mencius
Human beings might be able to live perfect lives if they had only these four kinds of motivations or emotional reactions to the world, but they have many other motivations. They include fear, anger, greed for wealth and power, sex, etc. Humans very easily learn that they can satisfy these drives more easily if they ignore the inputs from their virtues. For instance, a child who is large for his age may easily learn that he can take by force whatever he wants from other children his age.