Zixia and Zengzi were both students of Confucius. One day, they met each other on the street. Zengzi carefully looked Zixia over from head to toe, and then asked, "In the past you had many illnesses and were always thin and weak. You seem to have gained weight and look energetic too." Zixia happily said, "I have recently won a battle, so I feel very happy and have gained weight as a result."
Not understanding him Zengshi asked, "What do you mean?" Zixiao replied, "One day I was reading in my study books about Yao (2353 - 2234 BC) , Yu (21st century BC) and Tang (15th century BC). After reading their viewpoints on morality, friendship and loyalty, I found I appreciated their views and wanted to be a good person. However, when I walked down the street and saw so many tantalizing things and observed other people living in luxury, my desire for material things was stimulated and I wanted to make more money. These two opposing thoughts constantly fought inside my mind and I could not find any peace. I was not able to eat or rest well, lost weight and incurred many illnesses.
"Who won the battle?" Zengshi inquired. Zixiao quickly answered, "Yao, Yu and Tang's views on morality, friendship and loyalty won. As you can now see, I have gained weight."
Actually, from ancient times to today, there were many sages of virtue who realized that human beings' selfish desires are a form of material substance, a substance that is impure. This impure substance is a contributing cause to human illness. When human beings pursue personal gain, impurities continually accumulate in the body and cause illness. If a person can overcome selfishness and other bad thoughts, look lightly on money and material things, resist human temptation, and do things naturally instead of for personal gain, one will assimilate to the characteristics of the universe. One's realm and mind will elevate and the material of the body will elevate as well. One will be able reach a state free of illness or with few illnesses.