What is MIND ? Mind is not a thing, but an event. A thing has a substance in it, an event is just a process. A thing is like a rock, an event is like the wave; it exist, but is not substantial. It is just the event between the wind and the ocean; a process, a phenomenon.

So those who have known say that mind is like a bird flying into the sky - no footprints are left behind, not even a trace.