Try a little experiment. Close your eyes and say to yourself: "I wonder what my next thought is going to be." Then become very alert and wait for the next thought. Be like a cat watching a mouse hole. What thought is going to come out of the mouse hole? Try it now. Well? I had to wait for quite a long time before a thought came in. Exactly. As long as you are in a state of intense presence, you are free of thought. You are still, yet highly alert. The instant your conscious attention sinks below a certain level, thought rushes in. The mental noise returns; the stillness is lost. You are back in time.
— Eckhart Tolle