The human being believes that he is a personality, separated from the rest of the world. Already a mere reflection could teach him that he himself is no independent being in the physical. If temperature in this room was 200 degrees higher than now, we would not be able to exist here as we exist now. As soon as the circumstances change outside, the conditions are no longer appropriate to our physical existence.
We are only the continuation of the outside world and absolutely inconceivable as a special being. This is even more the case in the psychic and in the spiritual worlds.
We see that the human being, understood as a self, is only an illusion, that he is a member of the general divine spirituality.