Sara J. Schechner claimed that surviving glassware from the 15th and 16th centuries is far too imperfect to have been used to create realistic images, while "even thinking about projecting images was alien to the contemporary conceptual frame of mind."[16] Vincent Ilardi, a historian of Renaissance optical glass, subsequently argued against Schechner's conclusions based on surviving glassware, suggesting that the present condition of Renaissance glassware is not likely to reflect the optical quality of such glassware when it was new. Ilardi documents Lorenzo Lotto's purchase of a high-priced crystal mirror in 1549, bolstering the Hockney–Falco thesis in Lotto's case.[17] Furthermore, even normal eyeglasses (spectacles) can also project images of sufficient optical quality to support the Hockney–Falco thesis and such eyeglasses, along with magnifying glasses and mirrors, were not only available at the time, but actually pictured in 14th century paintings by artists such as Tommaso da Modena. Dutch draper and pioneering microbiologist Antonie van Leeuwenhoek (1632–1723), a contemporary of artist Vermeer (and an executor for Vermeer when he died in 1675) in Delft was known to have exceptional lens making skills, having created single small lenses capable of 200x magnification, far exceeding those of more complex compound microscopes of the period. Indeed, his feats of lens making were not matched for a considerable time as he kept aspects of their construction secret; in the 1950s, C.L. Stong used thin glass thread fusing instead of polishing to recreate Leeuwenhoek design microscopes. It was long believed that Antonie van Leeuwenhoek was a master lens grinder (a notion repeated in the recent BBC television documentary "Cell"). However, it is now believed[by whom?] that he came upon a relatively simple method of making small, high quality glass spheres by heating and manipulating a small rod of soda lime glass.[citation needed] https://en.wikipedia.org/wiki/Hockney%E2%80%93Falco_thesis