In his influential book Techniques of the Observer, Jonathan Crary traces the intellectual history of vision, visual technologies, and the interest in illusion. He starts with the camera obscura. In his analysis of this device, Crary closely follows Richard Rorty, who in his book Philosophy and the Mirror of Nature, describes the Cartesian intellect as a camera obscura – an empty, dark space in which images are projected onto a screen:

Crary in his own way repeats this important claim:

According to Crary, the camera obscura is an epistemological model because it transforms the randomness of sensory data into a rational, intellectual vision whose apparatus ‘corresponds to a single, mathematically definable point, from which the world can be logically deduced by a progressive accumulation and combination of signs. It is a device embodying man's position between God and the world.’

The assertion that the camera obscura, an instrument of illusion, was used in Descartes’ times as a model for rational understanding is, in my opinion, questionable. 4 But even more questionable is the way Crary uses it to describe the evolution of the conceptualization of vision inWestern culture. In his view, the camera obscura gradually loses its dominance as a model, and the objective rationality it guaranteed is progressively replaced by a conception of vision as subjective along with an acute interest in illusion, in particular in optical illusion. This shift from rational, objective epistemology to subjective vision and illusion, according to Crary, opens the way to all the innumerable nineteenth century optical toys, and eventually cinema.