The past world of man and the future world of man will always be in the imagination (an illusion) where true reality is kept at bay. But what does this really mean?
Man’s consciousness (vijñāna) is especially adapted to live in an illusory world and to even reproduce itself. It has not gone unnoticed by the Indian subcontinent that the world is an illusion and man, himself, is an illusory being who by his consciousness unknowingly clings to the illusion although intrinsically free of it.
A dualistic mind or consciousness is necessary by which to anchor itself in an illusory reality and to even survive it after the death of the illusory corporeal being, only to be reborn into another illusion.
In light of this, modern man tends to ground himself on one side of this duality that is the subject side (you could call it the knower, the observer or the experiencer). This side is always non-objective yet implicitly connected to the objective, a kind of negative unity.
Also desire is part of this duality. We could even say the desire of the subject to unite and become one with the object. But this too is an illusion. It is like looking at railroad tracks in the distance where they seem to converge, but really don’t. Thus it comes to pass that life is unfulfilling.
It was through Siddhartha’s awakening that he saw the way out of this almost hopeless predicament. Both subject and object were simultaneously transcended. This is naturally inconceivable for consciousness to wrap itself around or to even understand faintly. In terms of western consciousness it does not yet realize that it cannot ground itself on self-reflection.