The representation space of Renaissance painting is compared to the representation space of quantum physics in [this chapter]. The action of a “semi-transparent” mirror splitting the trajectory of a photon, or any quantum particle, resembles the action of “Alberti’s window” in painting. According to Alberti, painting must recreate a view through a window. To accomplish this task, the light coming from the scene (to be painted) must be caught by the painter’s eye and projected on the plane surface of an ideal veil. The pictorial image results from a “double projection,” for that window acts both as a glass intersecting the visual pyramid and as a mirror reflecting the painter’s eye. When Narcissus realizes how a mirror acts, the shadow which...