In the Light, Through the Sight

In the beginning Light begun, dispelling Darkness. It was the origin of the World. In the legend, light spread on a rock the shadow of a human profile. It was the Greek mythological origin of Drawing. In the XV Century, according to Filippo Brunelleschi experiments, and to Leon Battista Alberti treatise, Light intersected a flat ‘veil’. It was the origin of Perspective. The infinity was fixed on the image and the Euclidean space became larger. In the XIX Century, according to Claude Monet painting, Light return to touch the eye. It was the origin of a new sense of the space. Side by side with the birth of new Geometries, as well in the same years Felix Klein announced to mathematicians by means of the Erlangen Program. The fifth Euclidean postulate was exploded, with several extraordinary results. Among these, Relativity theory in science and the Cubism in art, sought after possible connections between space and time, the first by means of the physical properties of the Light, the second by means of the human properties of the Sight. Considering this series of historical revolutions in the system of geometrical and graphic knowledge, this paper aims to remark the role of the projective approach in the redefinition of the classical concept of space, even thanks to the ‘golden’ period between XVI-XVIII Centuries, when the heritage of Renaissance Perspective was largely and deeply diffused, and examined in depth, in Europe. As Erwin Panofsky said, in fact, it defined a special algorithm, producing “an objectification of the subjectivity”. First introduced by artists, in fact, this method, gradually improved, permitted also the scientists to consider the projective image as a valid scientific instrument to investigate, to hypothesize, and to discover some of the most general spatial properties of the space. Without renounce too much the visual verisimilitude of the geometric configurations. In this process, the Sight carried out a new task. Maybe, nothing strange if we consider it as a ‘middle point’ between the body and the mind. Or, mentioning the titles of two Ehrenfried Walter von Tschirnhaus volumes, between "Medicina Corporis" and "Medicina Mentis"