The Rainbow

Red, orange, yellow, green, blue, indigo, violet, from the base of the spine to the crown. The most recognisable esoteric image in the world after the pentagram.

It is ninety-nine years old and it is English. The spectrum comes from Leadbeater's The Chakras (1927); the traditional Indian sources give different colours, or specify none, and do not order them as a spectrum. The reason it feels ancient is that it is good design — a seven-fold system mapped onto the seven visible colours is instantly memorable, which is exactly why it displaced the material it claimed to describe.