Ultraviolet, Colour Beyond Sight

Ultraviolet is not a colour the eye can see: it is electromagnetic radiation of shorter wavelength than violet, discovered by Johann Wilhelm Ritter in 1801 when he found that invisible rays beyond the violet end of the spectrum darkened silver salts faster than visible light. Some animals, including many insects and birds, do perceive ultraviolet, and flowers carry ultraviolet patterns invisible to us that guide pollinators.

Because it lies just past the highest visible colour, ultraviolet functions symbolically in modern esoteric systems as the band above the crown, beyond the ordinary spectrum of the seven chakras, standing for the transpersonal or the spiritual reaches past individual consciousness. This usage is entirely modern, a product of twentieth-century aura and subtle-body literature that extended the visible rainbow of the chakra scheme into the invisible bands at either end. As a physical fact ultraviolet is simply high-energy light; the meanings attached to it are recent and analogical, built on its position beyond sight.