The placing of light sources is an intrinsic and an important part of the design process that plans and envisages the quantity and quality in vew of different effects. One could outline a series of exemples. In fact the light acts now as a compositive theme, that is current or periodical or diffused; now as an important part of the special context; now as a means of illustrating and exalting particular and special episodes of importance; then as occasion for contrast, and then for the identification of different areas; now as an illusion, also by means of refractions and mirrors and alterations of the actual dimension; as a shadowy creation and as an expression of the precousness of the materials and reflecting surfaces. This is not all, but enought to give proof of the expressiviness of a means that is particularly important, considering that in many cases natural light is not governable except on rare occasions due to the immoveable existing openings that are often insufficient if they exist at all. (Pier Carlo Santini, Gianfranco Frattini, Introduction, 1988, Edizioni Biblioteca dell´Immagine.