John Gage recounts the story told by the painter William Williams in 1787 about an entomological illustrator who, “living in a remote country, unacquainted with artists, or any rational system of colours, with a patience that would have surmounted any difficulties, had collected a multiplicity of shells of colour, of every various tint that could be discerned in the wing of that beautiful insect [the butterfly]; for he had no idea that out of two he could make a third, by this method he had collected two large hampers full of shells, which he placed on each side of him, …