The sound of one hand clapping.

What is the sound of the single hand? When you clap together both hands a sharp sound is heard. when you raise the one hand there is neither sound nor. The echo of the completely empty or heard from the soundless sound. 

This is something that can by no means be heard with the ear. It quite apart from seeing, hearing, perceiving and knowing if, while walking, standing an sitting. The sound of one hand clapping is a tiny sound that can be barly heard by humans.

The hand is the human heart and the clapping is emotions the other hand represents the one that makes us whole thus the clapping of both hands is the power of two people's emotions and the hands touching each other is the connection between the two people. 

The sound of one hand clapping is a conversation with someone that never connects with them so you try again and again before realizing you are only talking to yourself- they don't get it. If you never realize that, you are just insane by definition and you will continue to be the one hand that connects with nothingness.