Newton put it between blue and violet, though most people can't distinguish between blue and violet. Half way through the expert's lecture on Petrarch's view of ignorance, Joan whispered, This guy is an idiot. To see spectral indigo, you have to look at the reflection of a fluorescent tube on the underside of a blank CD. Intelligent, creative, sure of themselves, indigo children "often tell the parents 'who they are,'" though it's not clear here who "they" are.