knock on the sky and listen to the sound

What does this mean? As with most Zen sayings it means something different to each person. For me it means to take a moment, a sec, an hour and just look at something differently. This is something I do often. I hardly ever take anything at face value. Most times I will look at a situation and try to see the angles that no one else does. And in the same way people have to look at me this way. Don;t take me at face value because you will miss a lot.