I understand as follows:
* perception of reality = illusion (by Ego)
* insight of reality = reality (by Awareness)
David Bohm said, "The way we see depends on the way we think". So, everything depends on who "we" are. If we are ego (separate self), we think and what we see is the projection of our mind, namely an illusion. Meanwhile, if we are awareness (non-separate self), we don't think and can directly touch the reality as it is. In other words, we become one with the reality without differentiation between subject and object.
The Buddha advised us not to be fooled by what we perceive. He said, "Where there is perception, there is deception." The Buddha also taught on many occasions that most of our perceptions are erroneous, and that most of our suffering comes from wrong perceptions. And wrong perceptions are caused by ego's thinking (brain).
David Bohm also said, "Consciousness is much more important than money. Change in consciousness is essential." Yes, we can transform consciousness from ego to awareness only by one in-breath. And we can be always awareness (subconscious) through mindfulness, concentration and insight, like Buddha and Thich Nhat Hanh.