Light is the noblest of the natural phenomena because it is the least material and the closest to pure form. Gothic architects gave it the same metaphysical orientation as porportion or measure, which explains the interest in the use of stained glass to build ‘transparent’ walls.
Gothic innovation

Gothic architecture employed two new constructive elements: the pointed pointed arch and the ogival ribbed vault. These and other advances will make it possible to modify the mural and spatial structure of the buildings by using a new architectural scheme in relation to the supports. In temples with three naves, the buttresses are located in the side naves and the flying buttress is needed to transfer the forces of the roof to the exterior. The pinnacle is used to connect the buttress with the flying buttress and vertically deflect the resulting system of forces.
But it is not the use of the ogival rib vault or the arch that defines this style, nor is it the spatial verticalism. The difference lies in two features that lack previous precedents even in Anglo-Norman Romanesque:
- Light as the active principle of Gothic art with an unprecedented effect of luminosity.
- A new aesthetic and spatial conception between building form and function.
The stained glass window, the secret of light
The light floods the entire Gothic space in the form of powerful beams sifted by the stained glass windows whose colored rays are projected onto the mural surface. In reality, there would be much more light through these very large windows, but the architects are looking for something else. They pursue a surprising and transcendent effect that tries to elevate the faithful to a suprasensory sphere.
The light melts and transfigures the walls trying to dilute them in the reflection of the stained glass windows as if it wanted to turn them into themselves. The stained glass windows are dark, with blue and violet tones that create a supernatural effect in the interior that varies constantly according to atmospheric changes and the sun.
This light modifies the entire architecture and the material substance of the walls. It is projected on them and melts them, transfiguring them to dilute them in a multicolored reflection of stained glass as if they wanted to become themselves. There is no difference between transcendent light and material light: all manifestations of that light are reflections of divinity.

In contrast to Byzantine architecture, where the structure is invisible and the real skeleton of the building is not visible, the Gothic system is determined by the structural elements, which are all those that perform a function. Shapes are lines and volumes disappear.
Light and the union of form and function generate a new spatiality. Light is a source and beauty in itself and the great verticality of the central nave contributes to this, whose mural articulation does not reveal at any time what is sustained or what is sustaining. Only ascending forms that link with the ribs of the vaults, which are the point of union of lines of force, can be seen.
The Gothic temple seems to save the law of gravity more enhanced because nothing translucent from inside all the technical resources that are working to keep standing such a high work. There is a open space in the central nave, which is not delimited by a compact wall as a continuous mass, but by a fluid spatial background: that of the lateral naves, triforium and clerestory, where the stained glass windows radiate that suprasensory light that contributes to dematerialize the scarce stone surface of the pillars. There are no firm and appreciable spatial boundaries, but rather something fluid and very difficult to encompass.

The aesthetic vision of gothic architecture
Gothic architecture expresses a conception that turns the temple into an earthly transposition of the divine mansion and this affects the very valuation of architects as scientists who master mathematical theories and systems of proportions.
We can affirm that, in Gothic art, the aesthetics of light is directly related to the metaphysics of light. Cathedral builders use a system of proportions derived from the aesthetics of number present in the legacy of St. Augustine. Number can lead the intellect from the perfection of created things and thence to the invisible Truth which is in direct relation to the idea of God.
This is how the plan and elevation porportions are developed, where the architect resorts to the use of geometry through the use of a module based on certain regular polygons such as the rectangle, which we can find present (plans and elevations) in some treatises and graphic documents such as the architecture album of Villard d’Honnecourt.