What appears, now? Mountains and rivers? Do they really? How?
In pursuing the finest possible analysis, such as in Madhyamika Buddhism, one finds intellectually that "there is" nothing. Nothing ever appears but appearances -- like hallucinations in the deep night -- linked to conceptual activity.
But to Zen's direct perception, Nothing actually does appear, and one calls it "mountains, rivers, clouds, rain, starry sky."
"Mu" isn't just nothing -- it's the freshness and scent of these wild cherry blossoms. How inexplicably wonderful.
Trying to describe this, one is like a dumb person trying to describe an amazing dream. I know what it is for me. What is it for you?
"In absolute darkness, the mountains
respond to the temple bell."