Perspective is an approximate representation, on a flat surface (such as paper), of an image as it is seen by the eye. The two most characteristic features of perspective are that objects are smaller as their distance from the observer increases; and that they are subject to foreshortening, meaning that an object's dimensions along the line of sight are shorter than its dimensions across the line of sight.Only in our imagination do we live in more than two dimensions, and with its help we attempt to enliven the flatness of our image with depth. All of a sudden it may dawn on us how foolish we are, we faddists of the two-dimensional picture with our constant urge to achieve unobtainable depth.
-M.C. Escher, 1947