The world is blue at its edges and in its depths. This is the light that got lost. Light at the blue end of the spectrum does not travel the whole distance from the sun to us. It disperses among the molecules of the air, it scatters in water. (Solnit, 2006, p. 29).
So begins the chapter ‘The Blue of Distance’ in Rebecca Solnit’s book A field guide to getting lost. In the chapter she talks about the atmospheric conditions which create the impression that things seen from a great distance appear to be blue. Like distant mountain ranges. This blue is an illusion. Solnit compares this to the emotion of longing, as something that is ever in the distance, and never within close reach.
Both the blue of distance and the blue of longing are always far away, and can never be reached, because as soon as you get to the mountain ranges the blue will appear somewhere else on the horizon, always just out of reach. Rather like the rainbow, whose mythical pot of gold can never be found because the end of the rainbow is perpetually further away.
In 1690 Isaac Newton split white light with a prism into the colours of the spectrum, and noted these colours as: Red, Orange, Yellow, Green, Blue, Indigo and Violet. Newton claimed there were seven distinct colours where most would see only six. His inclusion of the colour Indigo, has been controversial. Named after a dye produced in India and valued highly in Europe (being called Blue Gold, to indicate its desirability), Indigo is described as being a colour on the spectrum between blue and violet, but is it only a shade of one or the other and not a distinct colour of its own?
It is thought that Newton, due to the conventions of alchemy, mysticism, and the science of the time (for which seven was a significant number) expected the spectrum to divide into seven distinct colours, and therefore perhaps invented Indigo in order to fit that assumption (Holtzschue, 2011, p. 135). When Johann Wolfgang von Goethe later wrote about colour theory, he revised Newton’s seven colours to the six we are accustomed to seeing in the colour wheel. (Holtzschue, 2011, p. 137).
A description of Indigo is usually as a dark blue (remember Newton’s contemporaries called the dye Blue Gold), or a blue-violet or purply-blue. It is contested territory.
Indigo is a colour that may not really exist. Perhaps it is an illusion, like the blue we see at the horizon, it disappears under close scrutiny.