What is Control Cycle?

The restraining cycle of the Five Elements: Wood controls Earth, Earth controls Water, Water controls Fire, Fire controls Metal, Metal controls Wood. In Liu Yao, a line controlled by the month or day branch is weakened. A jealous spirit (忌神) that controls the useful spirit is unfavorable.

Source: Bushi Zhengzong (卜筮正宗), Wang Hongxu, 1709