It's absolutely crucial that we don't conflate this internal reality with the external reality that it's tracking, because the two are very different. My brain's internal reality is like the dashboard of my car: a convenient summary of the most useful information. Just as my car's dashboard tells me my speed, fuel level, motor temperature, and other things useful for a driver to be aware of, my brain's dashboard/reality model tells me my speed and position, my hunger level, the air temperature, highlights of my surroundings and other things useful for the operator of a human body to be aware of.