Biologically speaking, our eyes basically sample what is out there. They can only detect things at a certain size, and they only detect at a certain rate. The rest of what we believe we see is made up by our minds. Essentially, we have a model that is built on many samples, and this model allows our brains to make up a whole picture out of the limited information our eyes provide.
Our brains have different, and sometimes very different ways of interpreting the little information our eyes provide. Just as an example, take one of those children who has been brought up living in the same closet for twelve years. When they are rescued, and they come outside, they have no idea what they are seeing, and no way to interpret the sight. This is because their eyes and mind have only trained on the closet, with straight lines and flat surfaces.
We are all different from each other in this way, although usually to a much lesser extent. Whoever said this, clearly perceived these hypotheses about how vision and mind work together.