Light is the soul of space, a breath that passes through it, giving it life. Chasing the shadow unabated, in a ritual that makes visible the passage of time. The architecture is, first of all, the implementation of this ritual that ignites the dialectic between fixity of space and dynamic action of light, between the finiteness of the measures and incommensurability natural element, between concreteness of matter and abstraction of the vacuum. This book provides system certain basic principles that govern the relationship between architectural space and natural light to put them at the center of the architect's work. 33 bicoloured illustrations