Chinese Perception of the Past and Future

下 can be used to refer to the future, for example 下周 (below week) means "next week". It is as though the past is seen as being above us and the future below.

 Secrecy Led to the Loss of Chinese Technological Achievem...

While these state records survive, most of the ancient Chinese literature on astronomy has disappeared. Because astronomy was so state-oriented, so security-bound, and so secret, the old astronomy books have left few traces. By contrast, the early books on mathematics, which were used by merchants, directors of public works, and military commanders, have survived in considerable numbers. Repeated imperial edicts enforced state security for calendrical science, astronomy, and astrology. In A.D...