It makes man feel happy with its brightness and sad with its absence. Our eyes move from brighter areas to lesser bright areas. Therefore it creates a sequence to make viewing an experience. Therefore important spaces, features and elements are subjected to more light. Light creates mystery, ambiguity and causing movement which makes spaces dynamic.
Light also creates patterns with shadow.
These patterns if created by natural light change direction and colour at different times of day. Elements like pergola cast shadows on exterior and even interior of buildings. Light infuses life into buildings. Ornamentation also renders character to space. Space is affected by projections which may cut and divide the space in several numbers.