She looked back at me, approving. "Yes! Exactly. A small fraction of the female population is tetrachromatic. They have an additional receptor in the eye that theoretically allows them to see colours that are not available to the rest of us, although because the tetrachromat population is so small we don’t have words for those colours, or even concepts for them. They exist only as something felt and experienced." She sighs. "I’m not one. I’d love to be, wouldn’t you? To see a broader spectrum, another dimension?"