One may think of metaphysics to be about the structure and meaning of reality as a whole. Metaphysics can explore reality using logic (also mathematics), reason, and empirical observation. But the ultimate arbiter of metaphysical theories is Zen or dhyana or the same, direct intuition of ultimate reality.
On the question of intuition, I have blogged on intuition before which for me is the better definition of dhyana.
Dictionary meaning of intuition: the act or process of coming to direct knowledge or certainty without reasoning or inferring: immediate cognizance or conviction without rational thought: revelation by insight or innate knowledge: immediate apprehension or cognition (Merriam-Webster Unabridged Dictionary).
What we have called in the past “mysticism” really has to begin with intuition which is the only way, as far as I know, of gaining direct access to the fundamental nature of reality. This would be the accepted Buddhist position. This falls somewhat in line with Bertrand Russell’s two kind of knowledge of truths, viz., intuitive and direct and that which is derivative and indirect which later became knowledge by acquaintance and knowledge by description.
Of course Russell was not a Buddhist monk whose mind was aimed at trying to see his true nature which would be kensho. Nevertheless what he had to say can easily be put into Zen. We can separate the intuition of our true nature from derivative and indirect knowledge which is certainly only descriptive.
I certainly like this distinction. It serves to make the Zen adept eventually give up derivative and descriptive knowledge which doesn’t really accomplish kensho. That can only be done through intuition which is probably one of the most difficult tasks a human can take take up to know the meaning of reality as a whole.