Glass and Natural Light in the Shaping of Sacred Space in the Latin West and in the Byzantine East

Undeniably, stained glass has a threefold value: functional, to protect from the elements and to admit light; aesthetic, to enhance the space and make one appreciate the colours of the décor through the admission of bands of coloured light directed by the shapes of the windows and the windows themselves; and symbolic, at least as far as Christian contexts are concerned, because the window is like a ‘jewel box’ that reveals the natural light, which is considered to be the greatest symbol of the divine. In this respect, questions arise about the role of concepteurs in the shaping of sacred space and in the ‘stage management’ of lighting. The importance of lighting devices in designing interiors has always – from Antiquity to the present day - been a priority for architects and patrons alike. In fact, ‘appropriate’ lighting is a major factor in our perception of spaces and, according to the circumstances, it can instill in the visitor a sense of brilliance, cleanliness, mystery, intimacy, and so on. In order to understand the extent to which light was meaningful to the designer (and the patron) of a sacred space, I decided to research into the practical purposes and the aesthetic aims behind the adoption of glass to fill the windows of the principal buildings in the West and the Near East between the times of Constantine the Great, Frederick Barbarossa and Manuel I Komnenos (4th to the 12th century). The abundance of archaeological material that had come to light in the last few decades has persuaded me to reconstruct the historical and cultural context of these choices. I found myself comparing the technical analysis of this material – in some cases mere scraps of window glass and stone, wooden or stucco frames – with the surviving literary sources. Some of the buildings involved in my study are the Constantinian basilicas of Rome, the Justinianic buildings of San Vitale and Sant’Apollinare in Ravenna and Hagia Sophia in Constantinople, the 6th -9th century basilica at Amorium, the Norman churches of Palermo, and the Comnenian Kariye Camii and Zeyrek Camii in Constantinople. Just as Heinrich Oidtmann did in the late 19th century and Enrico Castelnuovo did in the late 20th century, I worked on two levels, comparing the abundant new archaeological data with the written sources (enlisting the aid of philologists and art historians to avoid the misunderstandings that arose in Oidtmann’s day and were repeated subsequently). This approach was designed to permit to reconstruct, whenever possible, the role played by stained glass and, more generally, glazed windows in the design of decorated interiors. Sometimes the archaeological and literary data refer to buildings with important patrons, and this makes the research all the more fascinating, despite the fact that one has to deal with centuries for which little written information survives. In any case, I detected a third element that was lacking in the work of Oidtmann and Castelnuovo: an appreciation of the role of optics. Very few churches have been studied with this in mind. Although their original natural and artificial light sources (windows and lamps) have changed through time, they still offer interesting clues about this third element, that needs further consideration. In any case, light seems to have been planned to enhance the most important liturgical areas, and therefore to ‘shape’ the sacred space. Surprisingly perhaps, Byzantium, which traditionally plays no part in the study of stained glass, because it is thought to have had no role in its development, has offered valuable clues to the reconstruction of original sacred spaces through its fragmentary but historically significant coloured glass screens. Nevertheless, this is a field that awaits attention and a great deal remains to be done. Despite the highly informative role of art history in placing late medieval stained glass in its historical, aesthetic and socio-political contexts, little attention seems to have been paid to the effect these windows, and the light that passed through them, had on the people who looked at them. The majority of buildings with stained glass windows are churches and so we can assume that the majority of viewers were Christians, for whom the light played not only a ‘physical role (lighting the space, enhancing the décor, attracting attention and drawing the worshipper towards the liturgical focus of activity) but also ‘spiritual’ role as a symbol of God, as he is addressed in the Old and the New Testaments. For this reason, beginning in Early Christian times, great attention was paid to the lighting of churches through precious metal and glass lamps and colourful windows. The light changes its intensity with changes in the weather and with the different kinds of glass and materials used for the frames. Light, therefore, is really a ‘dynamic’ element in the creation of sacred space and as such it deserves our attention when we try to understand the intentions of patrons and/or concepteurs.