Sudden enlightenment in a nutshell

If we did the right kind of zazen we would discover something quite odd: we are not aware of the original source of our mental activity including the voice in our head.  We seem to be aware of only an unbroken continuation of our mental activity—not the original source of it.  Anyone who sits in meditation can verify this, personally. 

Next, if we assume that we are aware of our mental activity, but not the source, then what is this awareness of ours except a condition of dependence on our mental activity from thoughts, ideas and concepts, to emotions and internal dialogue.

This condition of constantly being aware of mental activity means also that we are always facing this activity so that we are constantly involved with it and entangled in it.  But what if for a very brief moment of time our mental activity unexpectedly stopped, what would we see?  It would logically be the original source.  And our awareness and the source would be single or one (eka).

Next, the problem is how do we get our mental activity to come to a halt? In Zen this is variously referred to as no-thought 無心 or no-mentation 無念, this being 頓悟 sudden enlightenment or kenshō (intuiting one's true nature).  This is a tough nut to crack.  I don't have an answer.  But needless to say it has been done many times.  We can read about it in the Kāyagatāsati Sutta (M. iii. 94) going back to the time of the Buddha.

Again, a monk who attains the Fourth Jhāna [dhyāna] has no suffering or happiness because happiness and suffering are eliminated and his former sorrow is eliminated. There is only equanimity which purifies mindfulness. The pure Mind suffuses every part of his whole body, like a man whose head is covered by a white cloth. There is no part of his body untouched by the white cloth.

I can assure the reader that this is a very accurate picture.  Mind is luminous and it suffuses even the adept’s thoughts no matter what is being thought of at the time.  This state lasts for about a day or two.  What is important to understand is that the adept is now one with the original source and over time will break the habit of identifying with mental activity, thus gaining power over this activity.  This is a conversion from a seeming dependence upon mental activity (samsara) to becoming independent of it (nirvana).