Based on the pure physiological reality, Sachs first divided dance into two categories: "uncoordinated" and "coordinated". He pointed out: "In these two dances, the physiological restrictions of the human body are lifted and the subconscious mind is brought into play. The difference is that in the dance that is not harmonious with human activities, it is accompanied by inhibiting the normal activities of muscles; In the dance coordinated with human activities, with the pleasant activities of muscles, this is an activity that moves forward without gravity. "