In our scientific age, we tend to see the rainbow as a purely optical phenomenon, or we might think of the end of the rainbow as the place where leprechauns hide the elusive pot of gold.
The Greeks believed the rainbow was a path between the earth and heaven. In Norse mythology the rainbow was seen as a bridge between Ásgard and Midgard, the realms of the gods and mankind respectively. In Chinese mythology, the rainbow was regarded as as a slit in the sky sealed with stones of five different colors.
In the story of Noah, the rainbow serves as a sign of God’s promise that the earth will never again be flooded. In the Stuppach Madonna by Matthias Grünewald (c.1475-1528), above, or the painting by Joseph Anton Koch (1768-1839), below, it serves more broadly as a symbol of God’s covenant.
Durer’s famous engraving Melancholia features a rainbow, though scholars differ on whether to read it as a hopeful or a pessimistic sign.
Next week we’ll look at rainbows in more scientific terms. But for now we might notice that Grünewald breaks a basic optical law of rainbows, namely that the colors of the rainbow should always be lighter than the background, because the colored light of the rainbow is added to the light in the scene behind it.
Further Reading: Rainbow Bridge by Raymond Lee, link.