All men within the four seas under heaven are brothers.

This is a quotation from The Analects of Confucius. The four seas refer to the seas on the four sides. The ancient Chinese thought that heaven was round and land was square, and China was located in the middle of the land, which was surrounded by four seas. The places within the four seas were all the territory known to them then.

The belief that "All men within the four seas under heaven are brothers" reveals the Chinese nation's concern for the whole world and kind offer of help to other people.

In his keynote speech at the Boao Forum for Asia Annual Conference 2015, Xi Jinping said: What China needs most is a harmonious and stable domestic environment and a peaceful and tranquil international environment. Turbulence or war runs against the fundamental interests of the Chinese people. The Chinese nation loves peace and has, since ancient times, held high such philosophies that "All men within the four seas under heaven are brothers."

四海之內皆兄弟

“四海之內皆兄弟”出自《論語》，意為全天下的人都親如兄弟。“四海”即東海、西海、南海、北海，古人認為天圓地方，中國居陸地中間，陸地四周由四海環繞。“四海之內”指當時已知的人類生活空間，“四海之內皆兄弟”彰顯了中國人兼濟天下的博大胸懷、仁愛友善的人文精神。

2015年3月，習近平在博鰲亞洲論壇年會上指出，中國最需要和諧穩定的國內環境與和平安寧的國際環境，任何動蕩和戰爭都不符合中國人民根本利益，中華民族歷來愛好和平，自古就崇尚“四海之內皆兄弟”等思想。