To tie it in a bit tighter with OPs article, I would just add that if we could only perceive two dimensions, the inner circle would disappear as we "move the circle up and away from the 2d plane".
It would only reappear to us once we moved it back down into our plane of perception, safely outside of the other circle.
The relevant bit from OPs article that this is analogous to is:
> "What would we see if you watched this happen in real life? Since we can't see anything outside our 3D slice of 4D space, from our perspective the moving (green) loop would disappear, to reappear later in the unknotted position."
To tie it in a bit tighter with OPs article, I would just add that if we could only perceive two dimensions, the inner circle would disappear as we "move the circle up and away from the 2d plane".
It would only reappear to us once we moved it back down into our plane of perception, safely outside of the other circle.
The relevant bit from OPs article that this is analogous to is:
> "What would we see if you watched this happen in real life? Since we can't see anything outside our 3D slice of 4D space, from our perspective the moving (green) loop would disappear, to reappear later in the unknotted position."