About perspective

It has been argued both Brunelleschi en.wikipedia.org/wiki/Filippo_Brunelleschi and Alberti en.wikipedia.org/wiki/Leon_Battista_Alberti were applying to painting the theories of medieval optics, which ultimately derived from the eleventh-century Arabic author, Ibn-al-Haytham, en.wikipedia.org/wiki/Ibn_al-Haytham known in the West as Alhazen, whose works were available in both Latin and Italian translations. These works on optics were about ‘Perspective,’ a term which meant ‘the science of sight.’. Alhazen had shown how light travels in straight lines, so that vision depends on a cone of straight lines extending outward from the eye to the object. Depth of field is thus not experienced directly, it is a result of binocular vision and of our capacity to interpret the way in which things closer to us look bigger and things further from us look smaller, so that, to judge distance, we need a reference point -- an object whose distance of size is known to us. It is easy to understand why Alhazen had concerned himself with how we see, not with how we might represent the world in a painting: representational art was forbidden in the Islam of his day. But it is harder to understand why his medieval successors had not developed his theories in order to show how they might be put to work by artists. ` Page 168