Editing Light (section)

===Classical Greece and Hellenism===
In the fifth century BC, [[Empedocles]] postulated that everything was composed of [[Classical element|four elements]]; fire, air, earth and water. He believed that goddess [[Aphrodite]] made the human eye out of the four elements and that she lit the fire in the eye which shone out from the eye making sight possible. If this were true, then one could see during the night just as well as during the day, so Empedocles postulated an interaction between rays from the eyes and rays from a source such as the sun.<ref>{{Cite book |title=Fundamentals of Optical Engineering |last=Singh |first=S. |year=2009 |publisher=Discovery Publishing House |isbn=978-81-8356-436-6}}</ref>

In about 300 BC, [[Euclid]] wrote ''Optica'', in which he studied the properties of light. Euclid postulated that light travelled in straight lines and he described the laws of reflection and studied them mathematically. He questioned that sight is the result of a beam from the eye, for he asks how one sees the stars immediately, if one closes one's eyes, then opens them at night. If the beam from the eye travels infinitely fast this is not a problem.<ref>{{Cite web |url=http://www-groups.dcs.st-and.ac.uk/history/HistTopics/Light_1.html |title=Light through the ages: Ancient Greece to Maxwell |last1=O'Connor |first1=J J |last2=Robertson |first2=E F |date=August 2002 |access-date=20 February 2017 |archive-date=19 March 2017 |archive-url=https://web.archive.org/web/20170319180859/http://www-groups.dcs.st-and.ac.uk/history/HistTopics/Light_1.html }}</ref>

In 55 BC, [[Lucretius]], a Roman who carried on the ideas of earlier Greek [[atomism|atomists]], wrote that "The light & heat of the sun; these are composed of minute atoms which, when they are shoved off, lose no time in shooting right across the interspace of air in the direction imparted by the shove." (from ''On the nature of the Universe''). Despite being similar to later particle theories, Lucretius's views were not generally accepted. [[Ptolemy]] (c. second century) wrote about the [[refraction]] of light in his book ''Optics''.<ref>{{Cite book |title=Ptolemy's Theory of Visual Perception: An English Translation of the Optics with Introduction and Commentary |author=Ptolemy and A. Mark Smith |publisher=Diane Publishing |year=1996 |page=23 |isbn=978-0-87169-862-9}}</ref>