In Letter on the Blind for the Use of those who can see (French: Lettre sur les aveugles à l'usage de ceux qui voient), Denis Diderot takes on the question of visual perception, a subject that, at the time, experienced a resurgence of interest due to the success of medical procedures that allowed surgeons to operate on cataracts (demonstrated in 1747 by Jacques Daviel) and certain cases of blindness from birth. Speculations were then numerous upon what the nature and use of vision was, and how much perception, habit, and experience allow individuals to identify forms in space, to perceive distances and to measure volumes, or to distinguish a realistic work of art from reality.