《黄帝内经·素问·六元正纪大论》
细心的观察时令，发病的情况是可以预测的，失于正常的时令及岁气运行的规律，则五行之气运行错乱，生长化收藏的政令，也就不正常了。
谨候其时，病可与期，失时反岁，五气不行，生化收藏，政无恒也。
If one observes the order of the seasons carefully, one would be able to predict the onset of the disease. The derangement of the five elements and the abnormal use of the rules of growth, transformation, storage and collection are all due to deviations from the regular and normal order of the seasons and the circulation of the Qi of the years.