So the corollory is we don't see objects we see the difference between objects. So there is no mental copy of the thing out there. Rather we are exquisitelty attuned to perceive difference, or as we say, we perceive by making distinctions.
So in a philosophic sense, there is nothing there from epistemology, we only infer there is something there from our perception of difference.
For instance, we know we are alive because we perceive the difference in our metabolic rate, and when there is no difference in our metabolic rate, we are flatlining and so dead.
So what's the difference? Only the difference between life and death.