But you forget that 'reality' is different for everybody.
Reality is not different for anyone.
Reality exists whether one person understands it or nobody, it just is.
What is different for everyone is how we understand the reality that is.
To some, ICE is cold, it makes things cold "Put ICE on that to cool it down".
In reality ICE is cold, it draws heat away. To put ice on that, warms the ice by drawing heat away from it.
Its the basic science of refrigeration.
People exist in a world of "Patterns of Familiarity". Reality is seen and associated then ignored and assumed. But...If the reality changes from our pattern, we recognize it again.
For instance, take the door knobs in your house.
While you were sleeping, someone moved all the door knobs in your house up 3 inches and inward two inches.
When you wake, you fumble for the door knob but it is not where you left it. Its still a door knob but it is now in a new location. Your pattern of familiarity has been broken. You see the reality. Eventually, you get used to the new location and you stop 'seeing' the reality.
People assign familiarity to reality all the time. Sometimes the familiarity distorts the actual perception of reality. When that happens, people think reality is a perception and mutable.
As 'reality; changes the understanding of the words in the book change as well
Reality doesn't change, the understanding of the word changes but the word always meant what it means, even when we didn't understand it. Our understanding didn't change reality, we changed to understand reality.
Reality does change. We live in a chaotic, evolving Universe that is always changing. Reality is simple but stark, cold and unemotional. Its difficult for an emotional creature like humans to accept reality.
We wrap associations, delusions and familiarity around reality so we can cope with its absolutes. This is why some people perceive different realities than others. Its a coping mechanism and is needed to keep us from going insane on the utter finality.
Some delusions are needed to maintain our sanity.
I have a passion for science fiction. Try to imagine how a robot sees the world. They are programmed to recognize objects yet form no associations or delusions to those objects. They might have the programming to understand the physics of that object but it holds no value to them except as the reality scanned. The writers give the robot personality, which gives it delusional associations towards the objects it encounters.
Science has already built robots. The real robots are not like the ones in books and movies. They are cold and precise, just like reality. Robotic programmers are working to give robots personality but it is difficult because the qualities needed to create a personality often conflict with the reality a robot must understand to function. The "AI" effect is fraught with problems because reality and perception change constantly.
Give a robot a red block and a blue block that are identical in every other way and ask it to choose the better block and it can't. But, change the reality by scratching a gouge in the red block and it 'might' read the blue block as the better of the two because it is pristine. If it doesn't read the scratch as a defect, it might still not be able to choose. It would all matter according to the perception programmed into the robots understanding.