Ever wonder why rocks are so highly esteemed in Zen?
They are esteemed because they exist in the realm of formlessness (the third world referred to in Buddhist sutras and chants that mention the three worlds).
The realm of formlessness is the last realm before Nirvana. Stones have transcended sense desire (the first world) and the desire to live in the world of form (the second world, perhaps reached only through the jhanas).
A stone has not attained Nirvana because Nirvana is inherent in all things and the world of formlessness is not Nirvana. But rocks are closer to Nirvana than those of us mired in the first world. Stones are also closer to Nirvana than the dwellers of the second world. So Zen practitioners admire rocks.
The book that best describes the jhanas of the second world and the immaterial attainments of the third world is Mindfulness, Bliss and Beyond.
