I love the exuberance of the medieval European aesthetic. One aspect of this aesthetic I find irresistibly attractive is the brightness and purity of the colors used in illuminating medieval manuscripts. In my amateur observation, medieval illuminators seemed to love two color pairings in particular: red and blue, and yellow and green.
The image below features the unpleasant subject of an eye operation, but it illustrates all four of these colors beautifully. Note the yellow border on the surgeon's green tunic.
Medieval manuscript illuminators did not simply color their pictures with whatever hues they felt appropriate. They followed carefully thought-out conventions and used a widely understood visual language to communicate nuanced political and theological ideas. Moreover, the colors were either limited to whatever pigments were readily available in the surrounding environment, or, if the artist were affiliated with a wealthy and well-connected monastery or town, he could avail himself of expensive imported pigments and dyes. Thus the colors used in any given image are neither arbitrary, nor chosen from a limitless palette. Similarly, until new discoveries in chemistry and technology allowed glassmakers to diversify their colors, medieval stained glass makers were more or less limited to the colors I'm discussing here: blue, red, green, yellow, and also purple and white. Given these limitations, it's amazing to me that medieval European culture produced such varied and creative images.
Let's first consider the blue and red combination. Blue is the color of deep heaven, and saturates medieval Christian imagery. Blue is also the color of grace, which is why the Virgin Mary is almost invariably depicted wearing blue robes or a blue veil. Medieval artists derived their brilliant blues from silver acetate, from indigo dye, or, most romantically, from finely ground lapis lazuli stone, sourced in Central Asia. In the image below, Christ sits enthroned in glory in a brilliant red ground, suggesting the Holy Spirit, against a blue heavenly background with gold stars.
Red is the color of passion, the Holy Spirit, and Pentecost. Different reds could be derived from various woods and plants (including rose and Brazilwood), insect dyes, or white lead (ceruse) roasted with fire until it turned red. This process produces a splendid red but is highly toxic. Check out the blues and reds on this series of scenes from the life of David.
On to yellow and green. Yellow is the color of renewal, hope, and light. To create yellow pigments, medieval artists had access to lead-derived yellows, yellow earth, arsenic sulfide, and a number of plant-derived dyes, including those from Reseda luteola and Crocus savitus. A lovely example of the yellow and green combination can be found on the breviary page below, which features a number of green plants resting on a yellow background.
And last but not least, green. Green, of course, is the color of nature, fertility, and new life. Medieval artists used copper sulfates and dyes derived from any number of plants, including buckthorn, cabbage, leeks, and nightshade. Here's another page from a breviary showing that lovely green and yellow combination.
Both of these color combinations—red and blue, and yellow and green—can be used to great effect in interiors. Navy blue and true red both work well as accents, and are more attractive together than separately. But this combination must be used sparingly; one wouldn't paint a wall in either shade. Yellow and green, by contrast, can be used liberally. Yellow and green is a very exuberant, life-affirming combination. What could be happier than a yellow flower amongst green plants?
Perhaps part of the great attraction of medieval colors is the fact that they are simply the historical primary colors we still teach to schoolchildren (red, yellow, and blue), plus green. At one time, in fact, these were considered to be the four primary colors. Goethe believed so and wrote about it in his book Theory of Colours in 1810. They are often still known as the "four psychological primary colors."
Without getting too deep into color theory or psychology, it seems to me that there is something comforting in the basic simplicity of these four colors. They are simultaneously ardent and calming. They all look lovely in combination with natural wood tones, grey, and white. I don't really follow a rigid color scheme in my own home, but if I did, these would certainly be central to it.