All movements come out of emptiness and the mind is the name given to this dynamic aspect of emptiness. It is straight, without ego-centered motivation. The emptiness is sincerity, genuineness and straightforwardness, allowing nothing between itself and its movements. Jeet Kune Do exists in your not seeing me and my not seeing you, where yin and yang have not yet differentiated themselves. Jeet Kune Do dislikes partialization or localization.
Totality can meet all situations.
When the mind is fluid, the moon is in the stream where it is at once movable and immovable. The waters ate in motion all the time, but the moon retains its serenity. The mind moves in response to ten thousand situations but remains ever the same. To change with change is the changeless state. Assume the pristine purity.