Knowledge Possessed by the Earliest People

Optical Lenses and Eyeglasses

If we go to our encyclopedia or history books, we read that lenses, be it in telescopes, microscopes or eyeglasses, are an invention of the last 400 to 500 years. Yet, there is evidence that early man had these devices long, long ago. In archaeologist Layard's book, "Nineveh and Babylon", chap. viii, pp. 16-7, he tells of finding a glass "lens of considerable power" along with two glass bowls in a chamber of the ruin called Nimroud. It is plano-convex, an inch and a half in diameter and 9/10th of an inch thick, giving a focus at 4 ½ inches from the plane side.

Considering the intricate and extremely accurate astronomical knowledge of the earliest peoples, it seems almost a necessity that they had some sort of devise with which to allow them to see the heavenly bodies more closely. Pliny, who was born about 23 AD wrote that in his day "articifers used emeralds to assist the eye, and that they were made concave the better to collect the visual rays". (Hist. Natur., lib. Xxxvii, c. v.) He even adds that Nero used such glasses when he watched the fights of the gladiators. Iamblichus, who wrote of the life of Pythagoras, wrote that Pythagoras 

"sought to contrive instruments that should aid hearing as effectually as optic glasses and other contrivances aided sight." (PN, p. 179.) 

Pythagoras lived in the 6th century BEFORE Christ. Plutarch speaks of mathematical instruments used by Archimedes "to manifest to the eye the largeness of the sun". Archimedes lived during the time of Alexander. These are just a very few of the many, many references to optical lenses. In fact, it appears that these were so common and everyday that little was thought of the importance of writing about them. But in time, knowledge of these devices grew less and less until it was lost until man "reinvented" the idea over 1,000 years after the last historical mention of them.