"Q: How can we restrain the mind? 

M: Will a thief hand over a thief? Will the mind find itself? The mind cannot seek the mind. You have ignored what is real and are holding onto the mind which is unreal, and are also trying to find out what it is. Was the mind there in your sleep? It was not, but it is here now. The mind is therefore impermanent. Can you find the mind? The mind is not you. You think you are the mind, and therefore you ask me how it can be restrained. If it is there, it can be checked. But it is not. Understand this truth by your own search. You will discover that searching for unreality is useless -- so seek the Reality, i.e. the Self. That is the way to control the mind."