This book proposes a general theory of perspective grounded in the concept of solid perspective, understood as a stable projective correspondence between real space and its perspectival image. Moving beyond the conventional limitation of perspective to the planar picture plane, the study argues that perspectival representation can also be generated within three-dimensional space, thereby defining what the authors term the space of representation: a unified system in which Euclidean space and projective space are placed in one-to-one correspondence. The volume reconsiders several fundamental issues in both the theory and practice of perspective. It examines perspective as both a three-dimensional and a two-dimensional construction, distinguishes between graphical and metric properties, and discusses reduction ratios, “true-to-scale” conditions, and the relationship between the observer and the representation of space in both three- and two-dimensional cases. Particular attention is given to the distinction between variations in the observer’s position, which alter the shape of the perspectival image, and variations in the position of the picture plane, which affect its extent. The book also addresses the long-standing debate concerning the relationship between perspective and human vision. Challenging the view that perspective must be observed with a single, fixed, and motionless eye, it argues that both planar and solid perspective can support mobile, binocular, and spatially dynamic observation, as demonstrated by historical and architectural examples such as Andrea Pozzo’s corridor at Sant’Ignazio, Bramante’s choir at San Satiro, and Borromini’s Galleria Spada. Within this framework, perspective is understood not merely as a conventional image, but as a robust representational system capable of producing a perceptual experience analogous to that of real space. Historical sources, from Guidobaldo del Monte to Poncelet and beyond, are re-examined in order to reconstruct the theoretical foundations of solid perspective. Finally, the book shows how digital modelling and computer graphics make it possible to construct solid perspectives and, through these models, to verify the fundamental principles of the space of representation from unprecedented points of view, thereby reopening perspective as both a scientific and an operative field of research.