The Art of War by active 6th century B.C. Sunzi

7. _Heaven_ signifies night and day, cold and heat, times and seasons.

[The commentators, I think, make an unnecessary mystery of two words here. Meng Shih refers to "the hard and the soft, waxing and waning" of Heaven. Wang Hsi, however, may be right in saying that what is meant is "the general economy of Heaven," including the five elements, the four seasons, wind and clouds, and other phenomena.]