All phenomena vibrate. There's no solidity anywhere, if you look closely enough.
When you stare at an object, peer all the way into the center. See what's there.
What is the essence of “staring at an object”?
I don't mean literally staring (although that works, too). Even in your mind's eye, you can stare.
What happens when you do that?
Can you find the solidity at the center of the object?
Waves propagate through a medium (air, water, space, luminiferous ether, consciousness, nothingness).
What is that perfectly static medium through which waves of attention are moving?
You know there's got to be something, or else you wouldn't be having the experience of “perceiving the object”.
I'm fairly certain, though, that the insistence that there are static frames of reference is what the Buddha meant by “craving” and “clinging”.
I haven't completely solved this puzzle yet.
But, we'll meditate on it tonight.