Ramana Maharishi

 There are three states only, the waking, dream and sleep. Turiya is not a fourth one; it is what underlies these three. But people do not readily understand it. Therefore it is said that this is the fourth state and the only Reality. In fact it is not only the Truth; it is your very Being. The three states appear as fleeting phenomena on it and then sink into it alone. Therefore they are unreal.