"When we are doing zazen, this line ZZ' is the reality of our lives right now, so we make every effort to keep to it. But we are not fixed and unmoving the way rocks are, so it happens that we tend to drift away from this line: thoughts come up or we doze off.
…This is b. If this b continues on to b' and b", we are actually dozing…Thinking and sleeping in zazen are pretty much the same.
…Sometimes we completely forget about where we are and what we are doing. We may chase after thoughts c, c', c" and end up completely separated from the reality of our life of doing zazen right now. Without being aware of it, we may start associating with or carrying on a dialogue with some vivid figure c''' that has been totally fabricated within our own act of chasing after thoughts.
…Actually, zazen is not just being somehow glued to line ZZ'. Doing zazen is a continuation of this kind of returning up from sleepiness and down from chasing after thoughts.
That is, the posture of waking up and returning to ZZ' at any time is itself zazen. This is one of the most vital points regarding zazen.
…Actually, ZZ' represents the reality of the posture of zazen, but the reality of our life is not just ZZ'. If it were only ZZ', we would be as unchanging and lifeless as a rock!
…The very power to wake up to ZZ' and return to it is the reality of the life of zazen. Zazen enables us to realize that all the thoughts that float into our heads are nothing but empty comings and goings that have no real substance and vanish in a moment.
…So we wake up to ZZ' and from the standpoint of waking up we are able to see that thoughts, desires, and delusions are all the scenery of life. During zazen, they are the scenery of zazen. There is scenery only where there is life. While we are living in the world, there will be happiness and unhappiness, favorable and adverse conditions, interesting and boring things.
…But my own true life is the reality of life that I wake up to without being carried away by the scenery. Zazen is the foundation of life where this reality of life is being manifested.
In that sense, zazen is the reality of the self—the true self. The essential thing in zazen is not to eliminate delusion and craving and become one with ZZ'.
Of course, there are times like this during zazen, but this, too is just part of the scenery of zazen. We aim at ZZ' even though we have a tendency to diverge from it. The very attitude of returning to ZZ' and waking up is most important for practicing zazen as the foundation of life."