Faced with the apparent banality of the initial question, the most intuitive answer would certainly be “blue”. In fact, the name of this colour in Latin is cæruleus, whose etymology goes back to the sky itself – cœlum – as if to define: blue equals celestial. However, the solution to the problem is not as obvious as it seems…
It is curious to note that in the paintings of antiquity, the sky was not depicted as blue, but white, gold or even red. The latter was the predominant dye of Roman fabrics, to the point where the term coloured – coloratus – became equivalent to red – ruber –, as it remains in one of its synonyms in present-day Spanish – colorado.
In practice, Greco-Roman culture considered red to be the colour par excellence. Blue, on the other hand, was considered a secondary or even hostile hue: Julius Caesar recounts that the British had their bodies coloured blue, “in order to appear more terrible in battle.”1 What is more, wearing blue was a sign of eccentricity and having blue eyes was a kind of anomaly…
In the patristic era, white was the colour most often recorded in texts, closely followed by red – 32% and 28% respectively – while blue remained practically forgotten – less than 1%.2 In the meantime, white became the “Christian colour” by antonomasia, symbolizing purity, holiness and glory. In the liturgical field, the clergy began to use the alb – from albus, white – for celebrations, as dyed fabrics were considered impure.
From the 9th century onwards, black, traditionally associated with mortification, became the virtually official colour of monastic habits, and this custom was reinforced through the influence of the monks of Cluny. The Cistercians, in contrast, began to associate black with luxury, so they adopted a habit of undyed wool, greyish in colour – hence their nickname the “grey monks”.
Later, Our Lady appeared to St. Alberic, abbot of Citeaux, clothing him in a white mantle, the colour henceforth adopted by the reformed branch, renamed the “white monks”. Years later, in 1124, Peter the Venerable, abbot of Cluny, wrote a disparaging missive to St. Bernard, abbot of Clairvaux, reproaching the Cistercians for thinking they were “the holy, authentic and only true monks in the whole world,” and “wearing the white habit,” a colour suitable for “joy and solemnities” and not for living a life of penance in this “valley of tears”…3
In reality, for the Saint of Clairvaux, whiteness was a symbol of detachment. Colours were steeped in materiality, unlike light, a symbol of spirituality. Thus, his churches were monochrome and devoid of images, except that of the crucified Christ. What for Peter the Venerable was a sign of conceit, for Bernard evoked sobriety!
Indeed, as Plinio Corrêa de Oliveira comments in Revolution and Counter-Revolution, colours can establish “certain states of soul” and “deeply influence mentalities.”4 In this vein, the 12th century represented a real counter-revolution in colours. For example, blue came to the fore because it was increasingly attributed to the Virgin Mary, whose garments had until then been painted in various dark shades, but rarely in blue.
With the Gothic period, everything became more sublime: as the architecture enabled the entrance of more external light and the enlargement of stained glass windows, colours began to emerge as something specific to luminosity – a fact proven today by physics. In fact, in the medieval world, light was the most “spiritual” visible element. After all, “God is light” (1 Jn 1:5).
And light was made. Blue, once considered the “colour of barbarians”, shone in stained glass windows, sparking healthy competition to achieve the archetypal blue: there was the blue of Saint-Denis, the blue of Chartres, etc., until the colour reached pre-eminence in the courts, notably that of St. Louis IX and his bleu royal – royal blue.5 The Germanic Blau stood out in heraldry.
In fact, for Suger, the craftsman of the Basilica of Saint-Denis, the cradle of Gothic, the splendour of the sacred precinct should symbolize the heavenly Jerusalem, whose walls are like a prism: “adorned with every jewel” (Rv 21:19). What is more, as an ardent lover of colour, Suger applied the variety of tones not only to the stone, but also to the fabrics, enamels and above all the stained glass windows of this “paradise” on earth.
Well, physics itself proves that we still only glimpse reality “in a mirror dimly” (1 Cor 13:12), because not only are we blind to capture the supernatural, but also an infinitude of colours in the spectrum. The rainbow alone has over a million colours…
So the sky is not painted with the indigo of Brazil’s oceans, nor with the polychromes of the Northern Lights, much less with the grey of post-modern megalopolises. The sky is, so to speak, “omnichrome”, or all colourful. Indeed, the human eye has never seen what God has prepared on high for those who love Him (cf. 1 Cor 2:9): a veritable divine aquarelle! ◊
Notes
1 GAIUS IULIUS CÆSAR. De bello gallico. L.V, 14, 2. In: Hering, Wolfgang (Ed.). C. Iulii Cæsaris commentarii rerum gestarum. Berolini-Novi Eboraci: Walter de Gruyter, 2008, p.73.
2 Cf. Pastoureau, Michel. White: The History of a Color. Princeton-Oxford: Princeton University Press, 2023, p.68.
3 Petrus Venerabilis. Epistola 28. Ad dominum Bernardum abbatem clarævallis. In: Constable, Giles (Ed.). The Letters of Peter the Venerable. Cambridge: Harvard University Press, 1967, v.I, p.57.
4 RCR, P.I, c.10, 2.
5 Cf. Pastoureau, Michel. Blue: The History of a Color. Princeton-Oxford: Princeton University Press, 2001.
