The very first Principle of Alchemy is that everything is Duality. To move from this duality back to oneness in this physical reality is not possible, even though it is desired by many seekers and promoted by many teachers. The moment you move into oneness you become One with everything that there is, everywhere, you become Oneness itself, you become the Creator. So, even if you find yourself closing your eyes and sinking into oneness (which is possible within yourself) the moment you open your eyes again you discover the reality of duality staring back at you. The harshest of all dualities, that of Life and Death, is just one of the many dualities that you face everyday. To be outside of Life is one way to overcome duality, however you will no longer have access to the sensory perceptions that you need to confirm which sort of oneness you find yourself in; a life before birth into this world, a life after death or some sort of unconscious experience in this life.
This drawing could be representing the oneness of our Universe. Yet you can see an outer circle and an inner circle, which could be an outer infinity and an inner infinity. Between these two infinities there is a world of reality that is cut off from these two infinities by a definite inner boundary and an outer boundary. By balancing the inner and outer worlds we have created a separated world for ourselves, our own reality cut off from the whole by the two boundaries. If you were to live in the outer reality or the inner reality you would also be cut off from the whole.
In our world of reality we are constantly balancing the two sides of every duality, but we never become one or the other even though some things give the impression of being singularities (one-sided infinities) such as gravity, entropy and time. And we never become the oneness itself. . . but we are working on it.
Our complete Universe is one whole, it is oneness itself. The only one who can truly ever see this oneness is the creator itself. You need to be outside of the whole to ever be able to see its true oneness, or you need to become the oneness itself and look into yourself, which is the same thing. This is the ultimate duality that we are in: outside the whole is one-thing and inside the whole is every-thing. Outside and Inside is a duality that we also call the zero dimension (this is the real fourth dimension). Ever understanding this duality is more of a philosophical quest than a scientific one. Our journey is one that takes us deep into the Philosophy of Duality. Are you ready?