In Liu’s overview step #6 is for spirituality, learn about the chi of spirit and emptiness so you can eventually understand the chi that enables you to know who you are.
For a very long time in Bagua, we try to find and understand yang. As we learn more and more neigung, our understanding grows. It gets more sophisticated.
Then at some point we begin to understand yin. And in a like manner our understanding of yin grows.
Then at some point we find both yin and yang. We begin to understand how intimately bound they are. We understand more and more about the dance between them until finally they are inseparable and always present. We have found both yin and yang.
But when the up/down, left/right, front/back, and in/out become balanced enough – we can start to perceive neither yin nor yang. This is first and foremost supported by the body and its physiology. All of the 16 part neigung is needed to reach this stage. It is all occurring simultaneously. It is all conscious.
The beginning stages of emptiness are based on the physiology and the conscious perception of the circulation of fluids in the body. The deeper meaning of in/out isn’t the inside and the outside of the body as much as it is the simultaneous flow of fluids out and in. This is what makes the internal arts internal and unique. Not forms. Not chi.