Once you preach, the point is gone.
Zen Master Gu Ja describes her first retreat
My seat was placed right in front of the wooden wall. The small piece of the wall in front of me soon turned out to be filled with constantly changing pictures. I saw pictures of beautiful landscapes, fields, trees, animals, faces of men and women, people dancing, laughing, making love and so on. I was totally fascinated and absorbed while looking at the pictures and forgot everything around me for many days. But one day it happened that suddenly all the pictures disappeared. The wall stayed just as it was with lines, dots, colors and wood grains. Simple and not changing. The view of this simple piece of wood could not be compared with anything else I had seen before. It was so clear and beautiful! This beauty touched me so deeply that I started to cry silently. But it wasn't until some years later that I could realize that what I saw on the wall and how I saw it had to do with my mind only. This small piece of wooden wall revealed obviously how my mind was moving and creating things. When our mind moves and thinking appears, out of the lines, dots and colors a tiger jumps out, demons are threatening, sex and rock 'n' roll emerge. It is the same in our everyday life. Our mind fabricates something, we think it's real and we laugh, cry and crave like mad because of that. We are like a fish fidgeting in the net of our own mind. Only when we realize that the substance of thinking and also the substance of our mind are all empty, we can let go of our attachment to our thinking and get out of the net. Everything then becomes simple and clear as it is. The wall is white and the sky is blue. Whatever we perceive, we are one with it. Only white and only blue.