Throughout history designers have attempted to introduce light in a way that an observer will be
conscious of the effect of light while the light source itself is played down in the architectural
composition. When light-transmitting (rather than opaque) material are prominently involved in
the lighting unit itself, the units become architectural forms and surfaces as well as lighting
elements. Such ‘self-luminous’ elements help to visually define a space and are important to the
general organization of the room. According to medieval thinkers, light was the source and essence
of all visual beauty, and is the principle of order and value. In a Romanesque church light is
something distinct from and contrasting with the heavy somber tactile substance of the walls.
The gothic wall in contrast seems to be porous, light filters through it. The gradual enlarging of
the window openings as such is not the most important manifestation of this process. The
sensitizing of the mass in terms of its role as either reflection or obstruction of the light flow radically
transforms the dynamics of the relationship and leads to an absolute plastic continuity of the architectonic
member to a rigorously logical connection of the elements.