An ‘enlightening’ interview with Michel Pastoureau, remarkable connoisseur of colors.
Where we speak again about the cathedral of Chartres and its famous blue…

Is it because we have learned to make it better?

No. There is no particular progress in the manufacture of dyes or pigments at that time. What occurs, it is a deep change of the religious ideas. The God of the Christians becomes indeed a god of light. And the light is… blue! For the first time in the West, the skies are painted blue – previously they were black, red, white or gold.
Moreover, it is then in full expansion of the Marian cult. Now the Virgin lives in the sky… In the images, from the twelfth century, she is dressed in a blue mantle or dress. The Virgin becomes the principal agent of promotion of the blue.

Strange reversal! The color so long barbaric becomes divine.

There is a second reason for this reversal: at that time, there is a real thirst for classification, we want to hierarchize individuals, give them signs of identity, codes of recognition. Family names, coats of arms, badges of office appear…
However, with the three basic traditional colors (white, red, black), the combinations are limited. More colors are needed to reflect the diversity of the society. Blue, but also green and yellow, will benefit. One passes thus from a system with three basic colors to a system with six colors. It is thus that the blue becomes in a way the opposite of the red. If we had said that to Aristotle, it would have made him smile!
Around 1140, when the abbot Suger rebuilds the abbey church of Saint-Denis, he wants to put everywhere colors to dissipate the darkness, and in particular blue. For the stained glass windows, he used a very expensive product, the caffeine (which will be called cobalt blue much later). From Saint-Denis this blue will spread to Le Mans, then to Vendôme and Chartres, where it will become the famous Chartres blue.

The color, and particularly the blue, became a religious issue.

Absolutely. Churchmen were great colorists, before painters and dyers. Some of them are also men of science, who dissertate on the color, make optical experiments, wonder about the phenomenon of the rainbow…
They are deeply divided on these questions:
– there are “chromophiles” prelates, like Suger, who thinks that the color is light, thus pertaining to the divine, and who wants to put some everywhere;
– and “chromophobic” prelates, like Saint Bernard, abbot of Clairvaux, who believes that color is matter, therefore vile and abominable, and that the Church must be preserved from it, because it pollutes the link that the monks and the faithful have with God.

Modern physics tells us that light is both a wave and a particle. We were not so far from it in the XIIIth century…

Light or matter… We felt it, indeed. The first assertion largely prevailed and, of the blow, the blue, divinized, spread not only in the stained glasses and the works of art, but also in all the society: since the Virgin dresses in blue, the king of France does it too.
Philip Augustus, then his grandson Saint Louis will be the first to adopt it (Charlemagne would not have done it for an empire!). The lords, of course, hasten to imitate them …
In three generations, blue became the aristocratic fashion. The technique follows: stimulated, solicited, the dyers compete in the matter of new processes and manage to manufacture splendid blue.