There are various things in the chain which represents. I first of the word "rine-tensei", a Japanese word which means a all living things being in flux through the endless circle of birth, death, and rebirth. People of older days thought that this was the system of the life and have to be a good person to be released from this endless chain to have to go to "gokuraku-jodo" which means like heaven. People who were bad or not good enough will rebirth and lead a new life in the same world without the previous life's memory.
Although the "rine-tensei" was thought as something like a curse, many things go round and round which makes it impossible to tell where is the starting place and where is the destination, making the symbol or the meaning of a circle "complete object".
