What is the sea?

What is the "sea"? In modern people's concept, it refers to "the part of the ocean near the land", but in ancient people's understanding, great lakes similar to the sea are also called "sea", and the names of Caspian Sea, Qinghai and Erhai Lake have been passed down to this day. The "sea" is vast, so it can also refer to things with "big" or "multiple" meaning characteristics: it can be called "many similar things are connected into large pieces", such as the "sea" of "sea of people" and "sea of fire"; It can mean "big capacity, big breath", such as "sea bowl", "public" and "sea boast" It is worth noting that "sea" can also mean "foreign", such as "sea" of "begonia" and "date palm". Accordingly, "domestic" refers to the territory of China, "overseas" refers to the territory of China, and "customs" is the state administrative supervision organ located at the border. Obviously, this usage of "sea" shows that people seem to regard "sea" as the dividing line between China and foreign countries. How did this strange understanding come about? To understand this problem, we have to browse the history of the ocean.

"Sea" used to be synonymous with direction, and there is a saying in ancient books that "the four seas still exist". This shows that in the eyes of the ancients, the sea is the end of the world, so it can be used as the name of the direction. The ancients formed this concept of space because they could get the answer from the pronunciation training of the word "sea": "Beauty is unlucky." "The sea, dark and ignorant. The practice of ancient people's voices is intended to reveal the reasons for the names of Chinese characters. Therefore, the interpretation of the "sea" in Darkness is actually explaining a historical fact: due to the lack of navigation ability, our ancestors had to look at the boundless sea, but they didn't know its details, let alone that there was a new continent beyond the sea, so they regarded it as the end of the world.

The Chinese ancestors thought that the Central Plains region of the Yellow River valley where they lived was the center of the world, so they called their country China. The aliens around China are considered to be around the earth, so they are also called "sea" because they are close to the sea. In ancient books, there is a saying that "Jiuyi, Buddy, Qirong and Liuman are called the four seas". In this way, the "sea" naturally becomes the boundary of the "China"; A series of words such as "domestic" and "overseas" are actually expressions of the ancients' cognition of "sea" through colored glasses.