From a Geometry of Vision to a Geometry of Light in Early Modern Perspective

Must the architect or artist understand how the world is perceived on the convex surface of the eye to simulate the three-dimensional world on a two-dimensional plane? For many earlymodern artists, optics – defined as the science of vision – was fundamental. Yet, for architects, the integration of optical theories into two-dimensional representations of buildings remained more tenuous. Architectural drawing depended on orthographic projection and the representation of built form through plan, section and elevation, which did not seek to mimic the process of vision. If anything, architectural drawing separated itself from the illusion of vision in its attempt to account for the discrepancies between the represented and the built form. Nevertheless, the shifting science of optics would come to influence the two-dimensional representation of the built world for both architects and painters. This essay covers a broad survey of perspectival treatises from the fifteenth to the eighteenth century in order to consider how changes in the science of optics shifted the means by which artists and architects theorized the representation of space and the simulated illusion of perspective. As will be seen, the seemingly innocuously obvious geometric parts for the creation of perspectival space – the Euclidean point and line – became obsolete in the eighteenth century due to fundamental shifts in the science of optics. Whereas once optics was a study of vision through points and lines, in the seventeenth century with the works of Johannes Kepler (1571–1630) and René Descartes (1596–1650), among many others, optics transformed into a study of light. As light rather thanvision became the focus of optics and its geometrical laws, the connection between a geometry of vision and a geometry of spatial representation became challenged. When light – not vision – became subject to the laws of geometry, the eye became one instrument among many (lenses, camera obscuras, microscopes and telescopes) capable of deception and fault. In turn, geometry lost its intellectual and metaphysical resonances and became a practical tool of application. The influence of the visioning technology of geometry on perspectival drawing for both the built and the figurative world lost its theoretical foundation. No longer a technology of vision, the art of geometry became reduced to non-theoretical rudimentary forms for beginning draftsmen