1000 to 1400: Optical and astronomical tool, entertainment Arab physicist Ibn al-Haytham (known in the West by the Latinised Alhazen) (965–1040) extensively studied the camera obscura phenomenon in the early 11th century. In his treatise "On the shape of the eclipse" he provided the first experimental and mathematical analysis of the phenomenon. He must have understood the relationship between the focal point and the pinhole. In his Book of Optics (circa 1027), Ibn al-Haytham explained that rays of light travel in straight lines and are distinguished by the body that reflected the rays, writing: He described a "dark chamber", and experimented with light passing through small pinholes, using three adjacent candles and seeing the effects on the wall after placing a cutout between the candles and the wall. Ibn al-Haytham also analyzed the rays of sunlight and concluded that they made a conic shape where they met at the hole, forming another conic shape reverse to the first one from the hole to the opposite wall in the dark room. Latin translations of his writings on optics were very influential in Europe from about 1200 onward. Among those he inspired were Witelo, John Peckham, Roger Bacon, Leonardo da Vinci, René Descartes and Johannes Kepler. In his 1088 book, Dream Pool Essays, the Song Dynasty Chinese scientist Shen Kuo (1031–1095) compared the focal point of a concave burning-mirror and the "collecting" hole of camera obscura phenomena to an oar in a rowlock to explain how the images were inverted: Shen Kuo also responded to a statement of Duan Chengshi in Miscellaneous Morsels from Youyang written in about 840 that the inverted image of a Chinese pagoda tower beside a seashore, was inverted because it was reflected by the sea: "This is nonsense. It is a normal principle that the image is inverted after passing through the small hole." English statesman and scholastic philosopher Robert Grosseteste (c. 1175 – 9 October 1253) was one of the earliest Europeans who commented on the camera obscura. English philosopher and Franciscan friar Roger Bacon (c. 1219/20 – c. 1292) falsely stated in his De Multiplicatione Specerium (1267) that an image projected through a square aperture was round because light would travel in spherical waves and therefore assumed its natural shape after passing through a hole. He is also credited with a manuscript that advised to study solar eclipses safely by observing the rays passing through