How do you know that there is a world outside of you?
All you know of the world is your perception. But is your perception outside of you?
All you know is the thought, the belief that there is a world outside of you. But that thought/belief is not outside of you. Is it?
It is intimately within you and is your own dream of sort.
You never know anything outside of awareness.
Your entire field of mind impressions is contained within awareness.
The belief in an external reality goes hand-in-hand with the belief in an internal personal self and is the cause of much misery and suffering.
The veil of ignorance.