Form is the visual shape of mass and volume. Light makes form legible. There is no form without light. The manner in which light renders mass defines the essential relationship between architecture and light. The appearance of form is interpreted through the direction and intensity of light. By altering the light you can not only redefine the shape of an object but also reinterpret its character and meaning. The form of architecture is thus entirely reliant on the presence and quality of light. the changing nature of natural light means architecture is being continuously, visually transformed. Light itself can have form but without mass. The shape of light can be defined through the way in which it is defined by the presence of mass.