To understand Mo-chao Ch'an, it is important to understand that while there are no thoughts, the mind also is still very clear, very aware. Both the silence (mo) and the illumination (chao) must be there. According to Hung-chih, while there is nothing going on in your mind, you are not unaware that nothing is happening. If your mind is unknowing, this is Ch'an sickness, not Ch'an. So in this state, the mind is transparent. In a sense, it is not completely accurate to say there is nothing there, because the transparent mind is there. But it is accurate in the sense that there is nothing there that can become an attachment or obstruction. At this stage, the mind is without form. Its power is there, its function being to fill the mind with illuminating power, like the sun, shining everywhere. Hence, Silent Illumination is the tso-ch'an in which there is nothing moving but the mind is bright, illuminated.