Master Woo Myung Words of Enlightenment – What does the koan, “What is this?” mean?

This koan asks about the origin of the subject, whatever it happens to be – object, vegetable or animal. Man is originally complete as a man, and all creations (things that are in existence) are all complete in their individuality, but they all came from me. This me is the energy of the origin – the original body of the Universe.
The metaphysical real substance is the mind. Everything in the world was born from this mind. Mind, that is the metaphysical real substance, is man’s real self, and this real self is the mother of all creations. Man is, in himself, a complete real substance as a man, but the place that this substance comes from and goes back to is the mind. If the subject of the koan, “What is this?” is a person, his complete or perfect self exists in the greatness of that mind. Therefore, the mind is mysterious and miraculous.

-Woo Myung-

https://santaclarameditation.blogspot.com/2021/03/master-woo-myung-words-of-enlightenment.html