I believe our understandings – sensemaking – is ultimately based upon physical systems but in the “compressed” format the brain uses.
https://en.wikipedia.org/wiki/Where_Mathematics_Comes_From covers some of the idea as it relates to mathematics for example.
As each metaphor lays upon each metaphor, the layers of abstraction remove it from its sources because the brain is capable of making connections that physical systems don’t seem to just yet. It allows us to imagine things-not-yet-possible (or perhaps not at all) but their basis (going right back to when we’re babies) I believe stems from there and builds upon it.
Well yes, the physical systems / body activities that make the initial connection from physical system/activity into a simplified compressed ‘brain’ format.
A lot of it is buried right in our language. Grasping an idea. Grasping a ball with your hands. Seems too simple, but it seems to be everywhere