First during medieval times yellow was replacing gold when it was too expensive for the project, like for example usage for the background in frescoes, large surfaces. Sometimes of course, gold was used on frescoes also, it depended on how much a community could spend. Yellow was a much cheaper alternative and still represented divine light. In an earlier post I wrote about symbolism of gold as representing divine light, as the color symbolism is theological). But yellow wasn't used symbolically only, also when needed to give some beautfil robe to a saint, for composition purposes, the color was used freely.
Chromatically yellow is also the lightest color from all chromatic ones. (White is non chromatic). Also it was used in illuminated manuscripts, as we see in this masterwork of medieval art: the book of Kells, from Iona, dating from the times when Irish monks spread their culture and knowledge in Europe. Columba was visiting Reichenau, as I told you before. This folio showing Christ enthroned makes use of yellow, which is fine of a color to even line the cross and painted as color of Jesus' hair. The birds are peacocks, about symbolism of this bird in this this article. The circles at the feet, surprise, surprise! Those are angels, called Thrones, often depicted as wheels, sometimes as wheels with eyes and wing, specially in medieval Byzantine art. Wanted to mention it, as they are not uncommon, and people wonder about what is it. But also can mean the heads of the nails of the cross. The book Christ is holding represents the divine law.
 | |
| Christus Enthroned, Book of Kells, Ireland, library of Trinity College, Dublin, via wiki commons |
The figures are angels, one angel is a seraf as the posture of his wings indicates (lower corner on the right, will write more about angels another time). This part of a wonderful lecture later describes the peacocks too: as incorruptibility of Christ's flesh, with chalices and hosts.
Closer to Renaissance the elevation of yellow to color of light started to diminish, when art started to be more realistic, the golden backgrounds fell out of fashion. Now yellow started to be viewed as color of falshood and treason. It was used to brand those who were considered socially less acceptable: prostitutes, Jews, heretics. Jews were ordered by law to wear yellow badge. About yellow as color of prostitution I wrote already when I wrote about Mary Magdalene.
And as we see in this fresco by Giotto, yellow was assigned to bad people.Jesus has a loving peaceful face, he is dressed in red and blue, Judas in all-yellow garment.
 |
| Giotto, Kiss of Judas, Scrovegni Chapel, Padua, Italy, via wiki commons |
Cathars after Albigensian Crusade were forced to wear yellow cross, as badge of shame. Of course they couldn't be Cathars by choice, they needed to provide prof of marriage and repent, than their live were saved. Repentant heretic was important, as too many heroic personalities burned on stake wasn't good advertisement for ideological side of religion. Some of information about Cathar religion we know from writing of a Cathar convert to Catholicism. Those crosses called las debanadoras were to be worn always outside the house. It depended on the depth of involvement in Catharism judged by the Inquisition in a trial of , if a person needed to wear one cross or two (front and back). Those crosses were usually six inches wide and had height of eight inches. Unless one was of aristocratic birth, the badge of shame was to be worn for the rest of someones life. Many simply didn't comply, or were unrepentant. It was not a simple badge of shame:Cathars didn't like the cross as a symbol, this refusal of the symbol was written in their religious philosophy. It was much more cruel punishement than a known more widely and younger scarlet letter for adultery. Following link will bring you the wikipedia articles about Cathars and yellow cross http://en.wikipedia.org/wiki/Cathar_yellow_cross
As for heresies: they were not considered a religious offenders only, but in Western Europe heresies were viewed also as treason against the state, and considered anarchy. This was also one of the reasons why it was relatively easy to prosecute those who didn't conform. Rulers were offended by heresies, specially because almost every heresy also criticized materialism of the status quo, preached poverty or renunciation of material world, Catharism did it to.
