Is what we see really there?

The pictures below inspire a very interesting question: Is what we see really there?  When viewing the two Hermann grids below, one can see how visual processing can often lead to surprising results.    In the Hermann grid on the right, we see gray circles that appear in the intersections of the white areas.  We see these two images as we do, because of Lateral inhibition. Due to Lateral inhibition, we see an illusion of enhanced lightness and darkness at borders of light and dark areas. We can prove that these circles are in fact an illusion, by looking directly into the intersection or by covering the rows of boxes leaving only one row exposed. These pictures have caused me to wonder about the the images we see and if  they are really there, or just illusions.