2.2. The development of the twin mode  

The phenomenon of the twin images appeared in literature has gone through several development phases. The origin dated back to the ancient Greek and Roman period. The twin image which was first mentioned in mythology can be regarded as the beginning of the twin mode. In the development process, the twin mode developed a lot in the literary realm and stepped into the mature period, which exerted great influence in later literary works. The develop processes of the twin mode are as follows:

2.2.1 Collective unconsciousness

Carl Jung was an excellent psychiatrist and one of his best known psychological concepts is the collective unconscious. The term refers to structures of the unconscious mind which are shared among beings of the same species. He argued that the collective unconscious had profound influence on the lives of inpiduals, who lived out its symbols and clothed them in meaning through their experiences. At the primary stage of human life, the primitive residents tended to believe that loneliness equals to death. In order to survive in the rugged environment, they must live in a group. They went out to hunt for food together, only in the form of teamwork, can their fragile life be perpetuated. Thus, the form of “group” is a mode of existence that the primitive residents must follow.