In a sermon delivered by the Dominican friar Giordano da Pisa, in the church of Santa Maria Novella of Florence, he celebrated the genius of mankind by stating that (translated),  "It is not yet twenty years since there was found the art of making eyeglasses, which make for good vision... And it is so short a time that this new art, never before extant, was discovered. ... I saw the one who first discovered and practiced it, and I talked to him." This preaching was of significant importance as it highlights the fact that the art of making eyeglasses was a gradual process and had existed for a while, but this knowledge had not been widely distributed for a long time. The image is from Wikimedia Commons and is available for public use.