Entering a Gothic cathedral on a sunny day means being enveloped by a light that is no longer that of the outside world. Passing through the stained-glass windows, sunlight is tinged blue, red, green and gold, and casts patches of colour on the stones and floors that shift slowly as the hours pass. This experience is not a secondary effect of the architecture: it was one of its main purposes.
Abbot Suger and Saint-Denis
Among the decisive figures of this transformation is Suger, abbot of Saint-Denis, near Paris, in the first half of the twelfth century. An adviser to the kings of France, Suger promoted the rebuilding of the abbey church, and in particular of the choir, consecrated in 1144. The new choir, with its wide windows and coloured glass, is considered one of the founding acts of Gothic architecture.
Suger wrote several works to describe and justify the building campaign. A central idea appears in them: material beauty, gold, gems, coloured light, can raise the soul towards spiritual realities.
The anagogical method
Suger calls this movement anagogical, that is, «leading upwards». On the doors of the church he had Latin verses inscribed expressing this idea: the dull mind rises to truth through material things, and, having been submerged, rises again on seeing this light.
Behind these words one can glimpse the influence of the writings attributed to Dionysius the Areopagite, a late antique mystical author who described the universe as a hierarchy of light descending from God and ascending back to Him. At Saint-Denis this author was then identified with the abbey's patron saint, and this identification made the adoption of his theology of light especially natural.
How a stained-glass window is made
A medieval window was built through a complex procedure:
- The glass was coloured in the mass with metal oxides during melting.
- The sheets of glass were cut into small pieces following a prepared design.
- The details of faces, drapery and hands were painted with a dark paint, grisaille, then fixed by firing.
- The pieces were joined with strips of lead, which formed the black outline of the figures.
- The panels were mounted on an iron armature inside the windows.
The lead, which separates the colours, has a symbolic as well as practical role: the dark lines make the light stand out, like chiaroscuro in painting.
The blue of Chartres
The cathedral of Chartres is famous for its medieval stained glass, largely preserved. Among it stands out a particularly intense blue, known as «Chartres blue». The window known as Notre-Dame de la Belle Verrière, with the enthroned Virgin, is one of the most famous examples.
Blue dominates many windows of the twelfth and thirteenth centuries, accompanied by red. The combination of these two colours produces, at a certain distance, a vibrant violet effect that fills the nave.
The Sainte-Chapelle
In Paris the Sainte-Chapelle, commissioned by Louis IX in the thirteenth century to house the relics of the Passion, takes this idea to its limit. The walls of the upper chapel are almost entirely replaced by stained glass, supported by slender piers. Whoever enters has the impression of being inside a casket of light, a kind of image of the heavenly Jerusalem described in the Book of Revelation, with its walls of precious stones.
The theology of coloured light
Why was coloured light so important? In medieval tradition light was considered the reality closest to God. But pure light is not seen: it is seen only when it meets something. The stained-glass window is precisely this encounter: divine light passing through matter, making it transparent and manifesting itself in colours.
| Element | Symbolic meaning |
|---|---|
| Sunlight | divine presence |
| Coloured glass | transfigured matter |
| Lead | the limit that makes form visible |
| Figurative narrative | sacred history becoming light |
| Moving reflections | time flowing in the liturgy |
A symbolic reading
The stained-glass window offers a powerful image of inner life. Like glass, the soul too can become transparent to light, letting itself be crossed without holding it back. And as light takes on colour passing through glass, so what we receive takes the shape and colour of what we are. No window is the same as another, yet all receive the same sun.
In short
- Gothic stained glass turns sunlight into coloured, symbolic light.
- Abbot Suger at Saint-Denis promoted an architecture of light in the twelfth century.
- The anagogical method raises the soul from material things to spiritual realities.
- Chartres is famous for its blue; the Sainte-Chapelle is almost entirely of glass.
- The window symbolises matter made transparent to divine light.
