Some historians believe that the binary number system has its roots in the concept of yin and yang —the ancient Confucian belief in two forces of nature that are separate, yet equal, which when combined represent the whole of existence. In the Chinese language, yang is represented as a solid line, whereas yin is shown as a broken line. As with the binary numbers of "1" and "0," the symbols for yin and yang can be combined to make many more characters.