ABSTRACT
The eidola theory addressed the physical basis for vision through the principle of nearby action and the simulative assumption. This assumption is that the starting point for vision is a simulation of the environment. A closely allied assumption, implicit in the simulative assumption but worthy of its own identity, addresses the question of what happens to these simulations of the environment. The simulative and projective assumptions of the ancient Greeks compose a causal theory of perception and the hypothesis of an internal agent. Alhazen’s elaboration of the inner observation entailed by the projective assumption was in keeping with Plato’s antithesis of body and mind. Locality is the keystone of science, passe and contemporary. If locality did not hold, then past and future would contaminate the present. Integral to emanation theory was the assumption that all causes are local or, similarly, all cause is by contact.
