What is Flying Spirit?

The visible line that occupies the position where a hidden spirit resides. In Liu Yao analysis, when a needed Six Relative is absent (hidden), the flying spirit at that position interacts with the hidden spirit through Five Element dynamics — generating, controlling, or clashing. Whether the flying spirit supports or suppresses the hidden spirit affects the reading's outcome.

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