This saying means that all the people in the world are as close as brothers. The Four Seas are the East, West, South, and North seas. The ancient Chinese believed that heaven was round and the earth was square, with China in the middle of the earth, which was surrounded on all four sides by the Four Seas. “Within the Four Seas” refers to the world inhabited by humans, which was also called “all under heaven,” referring to the whole country or the whole world. This saying shows the inclusive and broad mind of the Chinese and their compassion, love and friendship towards other human beings.
Four Seas refer to the territory of China or the entire world. The ancient Chinese believed that China was a land surrounded by Four Seas – the East, West, North, and South seas. The term suggests what the ancient Chinese conceived to be the map of China and the world: Nine zhou (regions) were located at the center of tianxia (all under heaven). Tianxia consisted of nine zhou and its surrounding Four Seas. China was within the Four Seas, while foreign lands were outside the Four Seas. In ancient China, Four Seas referred to all under heaven in most cases, and did not denote a specific body of water. Therefore, the term was used sometimes to mean the seas surrounding the land, and sometimes to specify the land surrounded by the Four Seas.
The basic meaning of the term is love for others. Its extended meaning refers to the state of harmony among people, and the unity of all things under heaven. Ren (仁) constitutes the foundation and basis for moral behavior. It is also a consciousness that corresponds to the norms of moral behavior. Roughly put, ren has the following three implications: 1) compassion or conscience; 2) virtue of respect built upon the relationship between fathers and sons and among brothers; and 3) the unity of all things under heaven. Confucianism holds ren as the highest moral principle. Ren is taken as love in the order of first showing filial piety to one’s parents and elder brothers, and then extending love and care to other members of the family, and eventually to everyone else under heaven.
Universal love, equal affection for all individuals, is a basic concept of the Mohist School of thought, as opposed to the principle of differentiated love advocated by the Confucian School. Universal love emphasizes that you should love others as you love yourself, and love others’ relatives and people of other states as you love your own so that all people would love one another equally. This principle of affection has no regard for blood ties or social status. It is an affection that is exercised equally without differentiating between individuals, families, or nations. If such a principle could be realized, we could avoid conflicts between persons, clans, or nations and bring equal benefit to all.
Bo (博) means extensive, wide; ai (爱) is synonymous with hui (惠) which means benefit to all. Ancient Chinese believed that ensuring the people a life of peace and security is hui. Love in turn is an expression of ren (仁) , or benevolence, which is based on close human relationships. The term applies primarily to a concept of governance of “love for and benefit to the people,” as demonstrated through its systems, laws, policies, and measures which should be as inclusive as possible. The term also refers to a kind of social morality and personal integrity based on harmonious engagement with others, goodwill, and mutual help.
On the semantic level, fan’ai (泛爱), like the term bo’ai (博爱), means a broad love that extends to all. However, in the history of Chinese thought, it has been used with a different connotation: while bo’ai generally suggests “love of all human beings,” fan’ai infers “love of all humans as well as all things.” It means the same as what Mencius(372?-289 BC) advocated that men of virtue should love others and treasure everything on earth, and what Zhang Zai (1020-1077)proposed that all people are brothers and sisters, and all things are companions.