Editing Persistence of vision (section)

===Historical references to afterimages and motion blur===
Aristotle (384–322 BC) noted that the image of the sun remained in his vision after he stopped looking at it.

The discovery of persistence of vision is sometimes attributed to the Roman poet [[Lucretius]] ({{circa|15 October 99 BC|55 BC}}), although he only mentions something similar in connection with images seen in a dream.<ref>Herbert, S. (2000). A history of pre-cinema. London. Routledge. p 121</ref>

Around 165 AD [[Ptolemy]] described in his book ''[[Optics (Ptolemy)|Optics]]'' a rotating potter's wheel with different colors on it. He noted how the different colors of sectors mixed together into one color and how dots appeared as circles when the wheel was spinning very fast. When lines are drawn across the axis of the disc they make the whole surface appear to be of a uniform color. "The visual impression that is created in the first revolution is invariably followed by repeated instances that subsequently produce an identical impression. This also happens in the case of shooting stars, whose light seems distended on account of their speed of motion, all according to the amount of
perceptible distance it passes along with the sensible impression that arises in the visual faculty."<ref name=smith>{{cite book|url=https://books.google.com/books?id=ASILAAAAIAAJ&q=ptolemy+potter's+wheel&pg=PA43|title=Ptolemy and the Foundations of Ancient Mathematical Optics: A Source Based Guided Study|first=A. Mark|last=Smith|date=29 October 1999|publisher=American Philosophical Society|access-date=29 October 2017|via=Google Books|isbn=9780871698933}}</ref><ref>{{cite journal|jstor=3231951|title=Ptolemy's Theory of Visual Perception: An English Translation of the "Optics" with Introduction and Commentary|first=A. Mark|last=Smith|date=29 October 1996|journal=Transactions of the American Philosophical Society|volume=86|issue=2|pages=iii–300|doi=10.2307/3231951}}</ref>

[[Porphyry (philosopher)|Porphyry]] (circa 243–305) in his commentary on Ptolemy's ''Harmonics'' describes how the senses are not stable but confused and inaccurate. Certain intervals between repeated impressions are not detected. A white or black spot on a spinning cone (or top) appears as a circle of that color and a line on the top makes the whole surface appear in that color. "Because of the  swiftness of the movement we receive the impression of the line on every part of the cone as the line moves."<ref>{{cite book|url=https://books.google.com/books?id=c6QKDgAAQBAJ&q=ptolemy+spinning+top&pg=PA137|title=Porphyry's Commentary on Ptolemy's Harmonics: A Greek Text and Annotated Translation|date=15 September 2015|publisher=Cambridge University Press|access-date=29 October 2017|via=Google Books|isbn=9781316239681}}</ref>

In the 11th century [[Ibn al-Haytham]], who was familiar with Ptolemy's writings, described how colored lines on a spinning top could not be discerned as different colors but appeared as one new color composed of all of the colors of the lines. He deducted that sight needs some time to discern a color. al-Haytam also noted that the top appeared motionless when spun extremely quickly "for none of its points remains fixed in the same spot for any perceptible time".<ref>{{cite book|url=https://books.google.com/books?id=3x0LAAAAIAAJ&q=ptolemy+optics+color+rotating+wheel&pg=PA444|title=Alhacen's Theory of Visual Perception: A Critical Edition, with English Translation and Commentary, of the First Three Books of Alhacen's De Aspectibus, the Medieval Latin Version of Ibn Al-Haytham's Kitab Al-Manazir|last1=Alhazen|first2=A. Mark|last2=Smith|date=29 October 2017|publisher=American Philosophical Society|access-date=29 October 2017|via=Google Books|isbn=9780871699145}}</ref>

[[Leonardo da Vinci]] wrote in a notebook: "Every body that moves rapidly seems to colour its path with the impression of its hue. The truth of this proposition is seen from experience; thus when the lightning moves among dark clouds the speed of its sinuous flight makes its whole course resemble a luminous snake.  So in like manner if you wave a lighted brand its whole course will seem a ring of flame. This is because the organ of perception acts more rapidly than the judgment."<ref>{{Cite book | url=https://books.google.com/books?id=xeaqDsktcc8C&q=%22every%20body%20that%20moves%20rapidly%20seems%20to%22&pg=PA132 | title=Notebooks| isbn=9780191608896| author=Leonardo da Vinci| date=2008-04-17| publisher=OUP Oxford}}</ref>

In his 1704 book ''[[Opticks]]'', [[Isaac Newton]] (1642–1726/27) described a machine with prisms, a lens and a large moving comb with teeth causing alternating colors to be projected successively. If this was done quickly enough, the alternating colours could no longer be perceived separately but were seen as white. Newton compared its principle to the sparkler's trail effect: a gyrating burning coal could appear as a circle of fire because "the sensation of the coal in the several places of that circle remains impress'd on the sensorium, until the coal return again to the same place."<ref>{{cite web|url=https://books.google.com/books?id=GnAFAAAAQAAJ&q=newton+Theory+about+Light+and+Colors&pg=PA123|title=Opticks:: Or, A Treatise of the Reflections, Refractions, Inflections and Colours of Light|first=Sir Isaac|last=Newton|date=29 October 2017|publisher=William Innys at the West-End of St. Paul's.|access-date=29 October 2017|via=Google Books}}</ref>

In 1768 [[Patrick d'Arcy]] (1725-1779) reported how he had measured a duration of 0.13 seconds for one full rotation of a burning coal while it was seen as a full circle of light. He registered multiple rotations with a purpose-built machine in his garden and with the collaboration of an observer who had superior eyesight (D'Arcy's own eyesight had been damaged in an accident). D'Arcy suspected that the duration may differ between different observers, light intensities of spinning objects, colours and viewing distances. He planned further experiments to determine such possible differences,<ref name="d'Arcy1768">{{Cite book |url=https://books.google.com/books?id=cL5eAAAAcAAJ&pg=RA1-PA439 |title=Histoire De L'Academie Royale Des Sciences. Année ... Avec les Memoires de Mathematique & de Physique, pour la même Année. Tirés des Registres de cette Academie |date=1768 |publisher=Boudot, Jean |language=fr}}</ref> but no results seem to have been published.