Colour a history of pigment
"Those splodges on old palettes turn out to be anything but mundane:
they contain real blood, squashed bugs, purple Phoenician seashells,
even ground-up Egyptian mummies.
For ultramarine, semi-precious lapis lazuli gets powdered
into whipped egg yolk like some celestial mayonnaise.
One hue was said to be obtained by collecting the urine from a holy cow
after it gorged on mango leaves.

(mmmmm...celestial mayonnaise!)