The great invention of eyeglasses was not based on the science of the time, but from craftsmen playing about with lenses, probably Venetian glass workers in about 1286. This made spectacles socially suspect to the aristocracy for hundreds of years, and unfortunately scholars associated weak eyes with weak brains, so they were worn in secret. The earliest spectacles were convex, for short sight. Concave glasses were not available before the middle of the fifteenth century.
Eyeglasses are perhaps the invention, next only to fire, that brings most aid and comfort. And what else works forever with no maintenance and no energy costs? Spectacles lengthen our effective lives as with their aid we can see to read and perform skilled tasks into old age. Before they were available, scholars and craftsmen were made helpless by lack of sight just as their skills matured.
The discovery that the lens of the eye works by simple physics — exactly like a glass lens — opened the mind to seeing our bodies as understandable through experiments and by analogies with the physical world. Seeing the eyes’ lenses as within physics, was a significant step away from the vitalism which blocked biological understanding, holding that every aspect of life is essentially unique and so beyond explanation. Our uniqueness is surely being able to question and discover, and sometimes to explain ourselves and what we see.
Eye and Brain: The Psychology of Seeing, Fifth Edition (Princeton Science Library)
Richard L. Gregory
Background on Richard Gregory