Concentration does not mean to concentrate on an external object; it is concentration upon life itself. It is a power of knowing, an intuitive mystical power which is not obtained by language. It is obtained by keeping your awareness upon the subtle actions that occur inside your thoughts, inside your body, inside the immediate ten inches or so that surround you, and inside your environment. With this mystical intuitive power, you know everything, including the sufficiency of your spiritual nature.
— Hua-Ching Ni, Entering the Tao