This illusion is all the contrasts, the black and white, up and down, good and evil, happiness and sadness, all happening in one immense simultaneity. In an unenlightened state, we cannot see the unity behind it. We believe the illusion and will run to the glittering pool of water on the road, believing it is real.
All the things that we see are not real in the sense too that they are perishable and keep changing. Enlightenment contacts that field behind this constantly changing landscape. It takes us to the origin of it all, where nothing changes.
What we see in the world is a combination of our optic nerve and its interaction with light, heat and a number of other variables. Yet if we walk into a door, we feel it and it hurts. The world does not feel like a simulation in such cases.
Enlightenment takes you into the unchanging background, where sensations of pain and pleasure are purely sensations, without all the psychological or fearful thoughts attached to them. You might feel the actual physical pain but without the fear, it becomes another cry of the body for attention. And you gladly comply with its needs. But you do not believe you are this body.