Conrad Fiedler's aesthetic of " visibility" is based on Kant's distinctions between two different modes by which we come to terms with reality: perceptual and conceptual cognition. Whereas the former is based mainly on visual experience, (even here the visual is given priority over the sensual -- see optic / haptic ) For Kant, conceptual cognition is arrived at through a process of abstraction, the conceptual ordering of perceptual data. Both are autonomous but at the same time equal processes.
If the intellect operates through the faculty of concepts, percepts (and art) take place in the realm of visual imagination or ideas (Vorstellungen ) But the bias toward conceptual thought has been so ingrained in Western consciousness, Fiedler argued, that it has now become difficult for anyone, most of all for the artist, to develop the perceptual faculty of visual experience. (Harry Mallgrave and Eleftherios Ikonomou, introduction to Empathy, Form, and Space, p. 30)
In Art and Experience in Classical Greece, J.J. Pollitt describes the Parthenon and its sculptures as requiring that it be simultaneously understood as something known and measurable and also experienced as a sense-impression, as something which the individual consciousness must sort out for itself in the unending fluctuations of light and dark. (p.83) According to Pollitt the classical style developed by Pheidias fused aletheia , reality known by abstraction (eg. mathematical proportions) and phantasia , the experience of things through the medium of our senses and brain. The "optical refinements" of the Parthenon and its sculptures (the building's subtle curvature, the entasis of the columns, thickening of the corners etc) show a tendency towards subjectivism in the design of sculptural form that addresses optical illusions and effects, whether they served to compensate for perceptual distortions, to exaggerate them, or to promote tension in mind between what the viewer expects to see and what he actually sees.