What is the underlying nature of all things?
What is the fundamental nature of all things?
What lies beneath?
What is just below the surface?
If you scratch reality, does it bleed?
Everything is real, but consists of mostly empty space.
As nearly all things can be broken down into their individual components, which can further be broken down into further components, then this asks the question: What things cannot be broken down?
What is permanent?
What is forever?
What is eternal?
I do not know.