Abstract: “Highest excellence as water” is one of the most profound propositions of the Tao Te Ching, written by Lao Zi. To understand this proposition, we can start with “friendship” which is a combination of “friend” and “goodness”. Based on the concepts of sincerity and personal loyalty, it also gets some connotations like intimacy, amity, treating and helping each other, and become a basic social morality. “Highest excellence as water” is the improvement in thinking of the ethical spirit of “friendship”. Seen originally, the concept of “Highest excellence as water” can date back to the traditional thinking, reflected in the ancient book named Luo Shu. In this book, north the direction symbolizes water and one the number, indicating a spirit of “imitating the law of nature”. Since the Han dynasty, Taoism uses Lao Zi's philosophy of “Highest excellence as water” to guide self-cultivation. This undoubtedly contributes to physical and mental health and longevity.

Key words: Friendship, Highest excellence as water, The dual cultivation of mind and body