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« Byzantine Art as Propaganda: Justinian and Theodora at Ravenna | Main | Philosophical Stages: Experimental pedagogy, performance, philosophy »

Abbé Suger and a Medieval Theory of Light in Stained Glass: Lux, Lumen, Illumination

Posted by Patrick Hunt

cathedrl.jpg InfAnnuns.jpg
Fig. 1 Building a Cathedral, Jean Fouquet, 15th. c. ; Fig. 2 Annunciation, Saint-Denis, 12th. c. (reconstructed)

In the new Gothic architecture - originally thought of by outsiders as "barbarian" in contrast to "Roman" - conceived and practiced by Abbé Suger at Saint-Denis, “the stained glass window held pride of place.” (1) Light was both subject and goal, the more light the greater. Medieval theories of light originated in a spiritualized world view and a philosophy whose sources were metaphysical in their history and their application. From biblical scriptures and patristic commentaries sprang a hermeneutic of light, whether allegorical or literal, and it is not surprising that these theories of light had their rationale basis in a tension that makes a certain sense today in physics (optics), however bathed in symbolism. This brief study delineates the source and basis for that rationale as outlined in Abbé Suger’s putative division of typologies of light into lux, lumen and illumination and the subsequent metaphorical application of colored light.

The monk Theophilus in De Diversibus Artibus, Book 3, Preface said, "If the eye of man...marks the abundance of light from the windows, it admires the inestimable beauty of the glass and the variety of the most costly work."

As Michel Camille and Michael Cothren have ably demonstrated elsewhere, the cathedral represented the new Jerusalem first intimated in Ezekiel’s apocalypse from the Old Testament (Ezekiel 40:2-43:27) and culminating in John’s apocalypse from the New Testament, where the cathedral becomes a representative Neoplatonic shadow on earth of the heavenly tabernacle. For Suger, the gates and foundations of Jerusalem were seen in the Book of Revelation 21:2-25 as precious stones:

“the holy city, new Jerusalem coming down from God out of heaven…having the glory of God, and her light like a most precious stone, even like a jasper clear as crystal…and the city was pure gold, like clear glass…whose foundations were garnished with all manner of gems: jasper, sapphire, chalcedony, emerald, sardonyx, sardius, chrysolite, beryl, topaz, chrysoprase, jacinth, amethyst…”

While colored glass had long been understood as a surrogate for precious stones, it is Suger more than any other who transformed the cathedral into this new vision, in some hope of bringing a foretaste of heaven on earth, perhaps even as a faith incentive for believers who lived in poverty. As Suger wrote, De administratione 23: “the multicolored loveliness of the gems has called me away…transporting me from material to immaterial things…26: the dull mind rises to truth through that which is material and in seeing this light is resurrected from its former submersion...33: Thus, when out of my delight in the House of God, the loveliness of the multi-colored gems has called me away from external cares, and worthy meditation has caused me to reflect, transferring that which is material to that which is immaterial... 34: [The Tree of Jesse window] urges us onward from the material to the immaterial...These windows are very valuable on account of their wonderful execution and the profuse expenditure of sapphire and colored glass.” In his dissertations and journals, “Suger …wrote explicitly of color. light and brilliance, all qualities of stained glass, as essential aspects of the purpose of religious architecture. He referred to ‘sapphire glass’ suggesting that the intense blue windows at Saint-Denis is to be understood as having the same importance as gems.” (2)

The first Gothic collection of glass that Abbé Suger innovated at St. Denis between 1140-1144 was tinged with a Dionysian “academism” (3) however steeped in mysticism. The root of this academic mysticism appeared to have a connection with Saint-Denis himself, as some clerical traditions maintained – however much in ahistorical error - that the martyr Saint Denis whose relics were the treasure of the abbey was somehow the same philosopher-cum-apostle in Athens converted by Paul (Acts of the Apostles 17:34). This belief was further stirred by the writings of Pseudo-Dionysius the Areopagite. author of Corpus Areopagiticum, and a Neoplatonist theologian circa 500 CE. Pseduo-Dionysius allegorized God as heavenly “light” and Jesus as earthly image thereof of that “Light” from the Gospel of John 1:4-5 and 9 "In him was life; and the life was the light of men. And the light shines in darkness, and the darkness did not overcome it...[He] was the true Light which lights every man who comes into the world." a metaphysical explanation of light taken from scripture or commentaries thereof. Much of the theological commentary as source writing about light was also found in Pseudo-Dionysius’ Peri theion onomaton (Greek) or De Divinis Nominibus (Latin) Divine Names, especially chapter 4. (4) Light in all its spiritual and physical manifestations was the very leitmotif of Suger’s Gothic transformation. Suger was familiar with Pseudo-Dionysius through the translation of John Scotus Erigena.

Although the new twelfth-century treatise De Diversis Artibus (On Various Arts) of the monk Theophilus was the practical source for making stained glass and how it could be optimally rendered from metallic oxides for colors in glass ,(5) Neoplatonic and medieval philosophy on etymology and scripture determined the actual choices and subjects of the windows, and Suger was certainly steeped in the latter as he guided the glaziers collected from all over Europe. Even though these glaziers had regional preferences and praxes, Suger unified them by moulding these differences to his vision,(6) "We also had painted, by the hands of many masters sought out in various nations, a splendid variety of new windows." (De administratione 24).

Contrary to curiously popular opinion that rendered stained glass as mere Biblia pauperum, a "Bible of the Poor", (7) Cothren has brilliantly and carefully shown that stained glass was conceived and executed, for example, at Beauvais but applicable in many contexts, as a sublime art with the highest aspirations in depiction of spiritual truths for the sophisticated as well as for the people. Stained glass was intended as a homily of great metaphysical depth far more than simple storytelling, where the color choices and patterns, allusions, heraldric devices and many other linkages also had profound meanings to be plumbed that were unlikely to be known by the illiterate; often windows told sophisticated stories and allegories deliberately using light as revelatory. (8) As agents of mutable light, these windows were far more than windows. This is also evidenced by Raguin and Manhes-Deremble, wherein those who often commissioned windows were not only wealthy patrons but well-educated in the subtleties and hermeneutics of scripture, literature, law and the arts. (9) Cothren has sluethed some of the Beauvais patrons like Bishop Jean de Marigny and his inspiring and yet personal vision for the windows there. (10) Homan also focuses on the theological role of art as religious instruction, far more didactic than Jerome's putative homilies at the Church of the Nativity at Bethlehem using wall mosaics as scriptural illustration. (11)

Suger could somehow parse three different Latin words for light: lux, lumen, illumination, likely derived in part from Avicenna's 11th c. Kitab al Shifa, although not all would agree Avicenna was sufficiently known before 1200. But Avicenna's contemporary Al-Haytham was the most probable mediator for this discussion that seemingly originated in Greek with Aristotle and then in translation via Greek and Arabic into Latin. Suger understood lux, external light as physical, coming from the sun and nature, especially light shining outside the cathedral. But once it entered through the window it was transformed into lumen, new metaphysical light because the glass, now both wall and sacred boundary functioned much like the ancient temenos threshold of a classical sanctuary or poemerium. On one external side it was ordinary and profane light that shone on everyone, even the heretic and the wicked (Matthew 5:45: “He makes the sun to rise on the evil and on the good”) , but on the other internal side the light was now consecrated and holy. Because “In Suger’s vision, light was the primary source of faith and divine inspiration”, (12) this light was one agency of a powerful benevolent grace that fed the soul. (Isaiah 9:2, “the people who walked in darkness have seen a great light.” This is where Suger extrapolates from Avicenna (lux, lumen): he understood that the light inside the cathedral was mediated by the gemlike windows, and this transformed light took a third route: once it passed through the physical eye of the believer, it was changed once again into illumination, now a spiritual light that elevated the mind and renewed the spirit within as a metaphor for internal life-changing light (Ephesians 5:8, “Now are you light, walk as children of light; I Epistle of John 1:7, “Walk in the light as He is in the light.”). Suger himself poetically described some of his windows, here the Burning Bush panel of the Moses window (Saint-Denis Abbey, North III): "Just as the bush is seen to burn yet is not consumed, So he who is full of the divine fire burns yet is not consumed."

Suger’s programmatic typology of windows also followed another allegory with its dominant use of two primary colors, not coincidentally the first two gems of the New Jerusalem, jasper (normally red) and sapphire (blue) in Revelation 21:19. Judging by extant window fragments, Suger certainly preferred blue (sapphire). Although allegories of color were not fixed then any more than now (and in fact were sometimes reversed), red often represented earthly passion, sanguinity of blood, and the corporeal body while blue, "the color of heaven" (13) was identified with spiritual aspiration, celestial sky and the promise of eternity. Naturally the two colors could be easily seen in the dualistic tensions of life as embattled humans have always been torn between two natures: body and soul, material and immaterial, earth and heaven. Humans vacillate between voluptuary desire and bodily asceticism in a tension mediated between the two extremes. (Romans 7:19 & ff: “For the good that I would, I do not; but the evil which I would not, that I do…I delight in the law of God after the inward man, but I see another law in my members, warring against the law of my mind…”). These are the very kinds of typologies Suger loved to make programmatic at Saint-Denis, (14) especially since he supervised and was the guiding mind behind the windows and the new construction to bring in as much light as possible. (15), although the dominance of red and blue glass is best seen in High Gothic. Only a short time later, Sainte-Chapelle culminates “the apotheosis of stained glass as a major formative element in the architecture.” (16) Who would have thought in the third millennium BCE when glass was first manufactured (17) that a building could have "glass walls" as at Saint-Chapelle? Although starting with Saint-Denis at the outset (1140-44), the great high Gothic windows of Chartres (twelfth to thirteenth century), Sainte-Chapelle, Bourges and Reims (the latter three from the thirteenth century) are the best examples of the medieval perception of tension of dominant red and blue glass that produce such visual and spiritual ecstasy in their viewers. Again at Chartres recently, applying fractal spatial analysis, I calculated in just a few windows how careful planning distributed and juxtaposed color patterns for maximum effect; accidental or casual color placement could hardly have resulted in such spectral color variability.

reims.jpg chartres%20joseph%20dream.jpg
Fig. 3 Reims, Rose Window; Fig. 4 Chartres, Nativity: Joseph's Dream

Perhaps it is too much to strain Suger’s understanding of this perceived tension into an allegorical aesthetic of a battle between the colors of red and blue in his windows even though they dominate all other colors. On the other hand, what might have been perceived as spiritual tension was actually a physical tension as physics has shown through optics: the retina cannot actually focus simultaneously on both ends of the visual spectrum. Although red and blue can be gazed at together at first without much trouble, ultimately the cone cells must polarize and choose either red and blue at either spectral end because of optical tension.

In 1907 physicist Gustav Mie, applying James Clerk Maxwell's equations on electromagnetic phenomena, including light, deduced and calculated glass color differences by light scattering through the various metal oxide nanoclusters dispersed in the glass: "how light in a medium gets scattered by particles on the size scale of the wavelength ("Mie scattering")" (18).

Fig. 5 Optics Color Spectrum

What Suger and his immediate successors, especially in France, understood intuitively as a mysterious allegory of red and blue hues and their metaphorical tensions, physics now presents as optical reality: the tension is sublime.

Fig. 6 Bourges Cathedral, The Life of Joseph Window, 13th c.


(1) Alain Erlande-Brandenburg. Musée nationale du Moyen Age, Thermes de Cluny. Guide to the Collections. Paris: Reunion des Musees Nationaux, 1993, 17.

(2) Virginia C. Raguin. Stained Glass: from its Origins to the Present. New York: Harry Abrams, 2003, 14.

(3) Louis Grodecki. The Stained Glass of French Churches. London: Lindsay Drummond, 1948, 14-6; Louis Grodecki. Les Vitraux de Saint-Denis I. Corpus Vitrearum Medii Aevi. Paris: Centre Nationale Recherche Scientifique, 1976. France Etudes I, esp. "Le Texte de Suger. La date et les circonstances de al creation", esp. 27, where Grodecki discusses and analyzes "relatif aux vitraux" the importance of Suger's own words: "Nous avons...par les mains tres expertes de nombreux maitres de diverse nations, une tres belle variete de nouvelles verrieres" ["We have..by the hands of numerous masters from different nations, a very beautiful variety of new glassmakers"], continuing discussion with the seminal Jesse Tree window.

(4) Paul Rorem. Pseudo-Dionysius: A Commentary on the Texts and an Introduction to their Influence, Oxford: Oxford University Press. 1993; Paul Rorem. Pseudo-Dionysius, The Complete Works. New York: Paulist Press 1987.

(5) George Seddon in Lawrence Lee, George Seddon and Francis Stephens. Stained Glass. London: Mitchell Beazley Publishers, 1976, 10, 68-9, 177-82. Theophilus and Life of Suger. Theophilus, De Diversis Artibus (On Various Arts); J, Hayward and W. Cahn, et al. Radiance and Reflection: Medieval Art from the Raymond Pitcairn Collection, New York: Metropolitan Museum of Art, 1982. On Theophilus’ treatise portion on stained glass, 12th c, , 39.

(6) Madeline Caviness. "Suger's Glass at Saint-Denis: The State of Research," in Abbot Suger and Saint-Denis: A Symposium, ed. Paula Lieber Gerson (New York: The Metropolitan Museum of Art, 1986), 257-72.

(7) although not necessarily a proponent thereof but in a more balanced critique: Madeline Caviness, "Biblical Stories in Windows: Were They Bibles for the Poor?" in B. S.. Levy, ed. The Bible in the Middle Ages: Its Influence on Literature and Art, Binghamton, NY, 1992, 103-47; and "Constructing and Construing Stories in Glass." Abstracts and Program Statements, College Art Association, 79th Annual Conference, Washington, D.C., 1991), 70.

(8) Michael Cothren. Picturing the Celestial City: The Medieval Stained Glass of Beauvais Cathedral. Princeton: Princeton University Press, 2006, esp. 71-96 with the Theophilus Window at Beauvais (and elsewhere in sculpture). This lavish book is probably the best-written tome on stained glass in the English language for demonstrating the often complex theology and philosophy behind this medium.

(9) Colette Manhes-Deremble. Les vitraux narratifs de la cathédrale de Chartres: Etude iconographique. Corpus Vitrearum France, Etudes II. Paris: CNRS, 1993, 5, 28, 72 & ff ; See a review of this thesis by Virginia Raguin. "Stained Glass in England During the Middle Ages: Book Reviews".Art Bulletin 77.2 (June, 1995) 321-24 and another by Alyce Jordan. "Review of Les vitraux narratifs de la cathédrale de Chartres: Etude iconographique by Colette Manhes-Deremble; Jean-Paul Deremble." Speculum 72.2 (April, 1997) 524-26.

(10) Cothren, 155-160 ff.

(11) Roger Homan. The Art of the Sublime: Principles of Christian Art and Architecture. Burlington, VT: Ashgate, 2006, 52: "Aquinas affirms the didactic function of religious art and gives the seal of his influential approval to the intricate symbolism..."

(12) Norman F. Cantor, ed. The Encyclopedia of the Middle Ages. New York: Viking / Penguin, 398.

(13) Peter and Linda Murray. Oxford Dictionary of Christian Art. Oxford: Oxford University Press, 2001 edition, 62.

(14) Wolfgang Kemp. The Narratives of Gothic Stained Glass. Cambridge: Cambridge University Press, 1997, 48. Kemp analyzes Suger’s typology in the stained glass programmatic display.

(15) Elisabeth von Witzleben. French Stained Glass. London: Thames and Hudson, 1968. “Saint-Denis windows before 1146 CE supervised – and themes decided – by Suger”, 20.

(16) Robert Sowers. The Language of Stained Glass. Portland: Timber Press, 1981, esp. 35-36 on Suger and glass history; E. H. Gombrich. “Eastern Inventions and Western Responses” , Daedalus: Journal of the American Academy of Arts and Sciences, Winter, 1998, 193-205 on enameling and lapidary invention. Glass as a borrowed pyrotechnology was a byproduct of Orientalizing metallurgy. The great architect and art historian Viollet-le-Duc postulated a controversial light irradiation in red and blue hues in the Gothic revival of the 19th c. as he experimented with color theory.

(17) Although the earliest known truly Christian stained glass windows - acknowledging San Vitale's sixth century fragments in Ravenna - may be at the Anglo-Saxon church of Jarrow circa 680 CE, glass manufacture in the ancient Near East and Egypt dates to the 3rd millennium BCE. John Harris and Carola Hicks. Discovering Stained Glass. Princes Risborough, Bucks: Shire Books, 1996 repr., 7.

(18) Phil Schewe and Ben Stein. "Beam Photography". Inside Science Research - Physics News Update Number 517.3. American Institute of Physics. 12/21/2000 (http://www.aip.org/pnu/2000/split/517-3.html); Chris McLinden, "Mie Scattering" 7/22/1999 (www.ess.uci.edu/~cmclinden/link/xx/node19.html).

Images courtesy of Bibliotheque Nationale, Paris (Fig. 1); Abbaye de Saint-Denis (Fig. 2) via http://vrcoll.fa.pitt.edu/medart/image/France/sdenis/windows/TwelfthcWindows.html; Diocese of Chartres (Fig. 3) via http://perso.wanadoo.fr/.diocese.chartres/cathedrale; Wikipedia (Fig. 5); Bourges Cathedral (Fig 6) Boston College, http://www.bc.edu/bc_org/avp/cas/fnart/arch/bourges_glass.html. Translations of Suger by David Burr.

Stanford University

Copyright © 2006 Patrick Hunt



I design, build, restore and teach classes on stained glass, and am deeply interested in the hisorical and metaphysical roots of the art form. This article is beautifully crafted to offer for the reader's contemplation the intriguing intuitive relation of Suger and the early glaziers to the physics and psychological impact of pure tones of transmitted light. As far as the metaphysical background, there is verse in the Torah that says the people of God shall where a ribbon of blue ( I think around the hem of their garments)because they shall be holy, thus associating the color blue with the concept of holiness. Also the pomegranates in the temple and I think the priests garments were to be blue. Interesting because it is a symbolically transformative coloristic abstraction.

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