“To be is to be perceived” is the key statement in George Berkeley’s philosophy. However, as a Kung Fu practitioner, to be is to perceive.
Since Qi is invisible and intangible, you can only learn it by your ability to perceive.
The start point of acquiring intangible aspect of kung fu is to catch feelings you get from direct contact with your teacher. These feelings make you know what ‘Qi’ is and how ‘Song’ is like. You experience how to direct Qi back and forth with your spirit. These feelings will be guiding you when you practice. They become the lamp for your feet and the light on your path.
In solo practice, you need to perceive if your Qi is present in your every movement. You need to perceive that your Qi fill the space around you, expands, falls in, and expands again. Your Qi grows stronger through this process.
In real combating situation, you need to perceive and discern how your opponent’s Qi moves and then give the appropriate response.
In ancient times, some people could feel the subtle changes outside without any instruments, such as weather and climates. They perceived the changes with Qi. As for them, emptiness in space did not mean nothingness. The empty space was filled with something invisible, like energy. They used Qi to interact with the energy in space and cultivated stronger Qi.