I think all of the quotes I have here, point to the same idea.
lmk what you think, I'm interested in other people's ideas on this theme.

Kuei-shan asked Yang-shan, "How do you understand the immaculate mind?
"Yang-shan replied, "Mountains, rivers, and plains; sun, moon, and stars."

Wind, flag, mind, moving,
All equally to blame.

Space is the Dharma body and the Dharma body is space.

It is like the great orb of the sun risen in the sky, which illuminates uniformly throughout the ten directions.

The brilliance of the Buddha illuminates the whole universe

諸方深與淺 The depths and shallows of the world
都在掌握中 are all in its grasp.
□天□拄地 It supports the heaven and sustains the earth.

One day, standing near the Dharma Hall, Mumon heard the sound of the drum signaling lunchtime and was suddenly enlightened and then he made a poem about it:

A peal of thunder under the bright blue sky!  

The multitude of living beings on earth have opened their eyes.
All things in the world bow alike.
Mount Sumeru jumps up and dances.

Monk: How about when they say the sound of the rain has given you a sermon?
Is that correct?
Foyan: I do not agree; the sound of the rain is you giving a sermon.

If you are able to see, this is only the mind that reflects the realms.
If you use a mirror to reflect your face, even if you are able to see your features clearly
this is fundamentally only an image.

The six sensory capabilities each deals with sense objects:
the eye deals with forms
the ear deals with sounds
the nose deals with fragrances
the tongue deals with tastes
the body deals with tactile sensations.
Between [these senses and sensations] are generated the six consciousnesses. These are the eighteen realms.
If you comprehend that the eighteen realms do not exist, [you will understand that] the six [sensory capabilities] combine together to form a single vital brilliance. The single vital brilliance is the mind.
Trainees all understand this but they are merely unable to
avoid forming interpretations of the vital brilliance.