What is meant when Ramana or Robert Adams says “the world is not real. You are not real. You do not exist. The world is in appearance, an illusion”?
Several things are meant, and all of them are based on experience rather than a philosophical viewpoint. That is, yogic experience, not every-day, “common sense” notions of concepts.
1. The first “reason” appears at first to be philosophical, but actually rests on experience. This reason is that nothing lasts, everything is constantly changing, from the mind, one’s body, the seasons, weather, climate, and even the rising of mountains and their subsequent erosion away. No object lasts. No object endures. Nothing is self-sustaining in the objective world of objects. Seeing under the aspect of eternity, nothing lasts, nothing persists, not even the world for the universe. As such it is not real in the sense of being self-sustaining, self caused, and eternal.
2. In the moment of first awakening, when one first realizes the Manifest or divine Self, the life force, Shakti, acting in conjunction with consciousness, and one loses primary identification of the body, and re-identifies as consciousness, the way consciousness is perceived changes radically. Consciousness becomes one’s primary identification, and everything is realized as being just an appearance within consciousness, an object within the field of consciousness, and as such, is not independent of your consciousness. Nothing is independent of you as consciousness. It does not have an independent existence. It is just an appearance in consciousness, including the appearance of your own body. Everything is just in appearance in consciousness. The operative word is “appearance.”
3. The other thing you have to realize, is that this point your experience of consciousness itself changes as opposed to before when you felt you were dealing with objects that had the same reality as you, as a physical body. One experiences the world differently. It is a safe place now as it is no different than you are as body/mind. Both are appearances within the one consciousness. Also, consciousness seems far more intimate than a supposedly separate and objective world of coequal objects. They become “your” objects. And reality no longer seems as solid. It flows. Nothing appears solid anymore because everything is permeated against a background of emptiness, and things flow out of emptiness and back into emptiness. It is not just a concept, you actually witness the coequality of form and emptiness and their indivisible interplay.
4. But after a while of dwelling in and identifying with consciousness instead of with the body, one realizes that consciousness itself is temporary, ever-changing, and is not self-sustaining. So, just like when a dream ends, the dream world disappears into the unconscious, into nothingness, so when the body dies, the sense field and the sentience associated with that physical body just disappears, and is absorbed into the nothingness which proceeded its birth. Consciousness comes out of nothingness, and at the end of one’s life span, is recalled into nothingness. It is a temporary show. Thus, while everything is consciousness, is known through and by consciousness, and is an appearance in consciousness, consciousness itself is just an appearance within nothingness.
Thus, understand Robert and Nisargadatta when they say world is not real, it is an optical illusion, it is Maya, means that the entire “play” of consciousness has the same reality as a dream, same origin, and the same end. It suddenly appears from out of nothingness, just as a body is born and sometimes later consciousness begins. When the body dies, the associated consciousness is absorbed back into nothingness, which some call the absolute.
It cannot be understood from the Western point of view where all objects are considered to be independent of consciousness and consciousness merely illumines the existence of relatively stable external objects that exist independently consciousness, and you are but one object among many, some of which are sentient, and others, like rocks appear to not be conscious. As long as you identify your body as you, and consciousness as the instrument for perceiving a real external world, you can never understand the point of view that no object is real, including your body, or your mind, or your emotions. All these are constantly flowing, mixing, combining and recombining, flowing out of emptiness and then disappearing back into emptiness or nothingness.
Therefore, Buddhists say form is emptiness and emptiness is form. Forms have the essential quality of being empty, nothing, and in that sense they do not exist. They appear out of emptiness, or nothingness, in the same way as the entire universe is supposed to have been born, out of nothingness, in a big bang 13 billion years ago, and they returned to emptiness or nothingness at the end of the universe when all the particles in the universe become dispersed into nothingness.