We wanted to see the veins in your arm - a fine web of navy rays that usually appear like kaleidoscopes of red light behind closed eyelids - but the sun was already set and we couldn't distinguish them from the blueing atmosphere around us. Black light tells us nothing; blue light makes you dark; dark like that time you slept so long on the beach that you became the only distinguishable colour in an oversaturated landscape. Wish-you-were-here postcard colours.