To me personally, the most remarkable and, in the long run, the most influential man who was translated was not a Greek. That is because I am interested in the perception of objects in space. And that was a subject about which the Greeks were totally wrong. It was understood for the first time about the year AD 1000 by an eccentric mathematician whom we call Alhazen, who was the one really original scientific mind that Arab culture produced.{{U}} (66) {{/U}}Alhazen first recognized that we see an object because each point of it directs and reflects a ray into the eye. The Greek view could not explain how an object, my hand say, seems to change size when it moves. In Alhazen's account it is clear that the cone of rays that comes from the outline and shape of my hand grows narrower as I move my hand away from you.{{U}} (67) {{/U}}And that, and only that, accounts for the difference in size. It is so simple a notion that it is astonishing that scientists paid almost no attention to it for six hundred years.{{U}} (68) {{/U}}The concept of the cone of rays from object to the eye becomes the foundation of perspective [透视画法]. And perspective is the new idea which now revivifies mathematics.
{{U}} (69) {{/U}}A manuscript of Alhazen's Optics in translation in the Vatican Library in Rome is annotated by Lorenzo Ghiberti, who made the famous bronze perspectives for the doors of the Baptistry in Florence. He was not the first pioneer of perspective--that may have been Filippo Brunelleschi--and there were enough of them to form an identifiable school of the Perspectivi.
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A. It was a school of thought, for its aim was not simply to make the figures lifelike, but to create the sense of their movement in space.
B. The Greeks had thought that light goes from the eyes to the object.
C. The excitement of perspective passed into art in north Italy, in Florence and Venice, in the fifteenth century.
D. As I move it towards you, the cone of rays that enters our eye becomes larger and subtends a larger angle.
E. Above all, we feel that the painter's eye is on the move.
F. But artists attended to it long before that, and in a practical way.