The Latin word cornix — the crow — has been beloved of punsters for millennia now. Medieval schoolboys learned that
cornix est alba si cor tollatur ab illa.
Giordano Bruno recorded another one in his Spaccio de la bestia trionfante, mocking the “childish sophistry” that could delight in a line like
cor est fons vitae, nix est alba, ergo: Cornix est fons vitae alba.
Silliness aside, it turns out that by 1687, we actually knew how to produce white crows — or at least one bird seller did.
In the markets of Frankfurt in that year, eight white crows were offered at a very high price; their owner shared his recipe with the Eisenach physician and scholar Christian Franz Paullini:
Rub newly laid crow’s eggs, the fresher the better, with the grease of a white cat; coat them with the brains of the same cat, then give them to a young white hen that has laid only her first egg to incubate. During the entire period of incubation, keep the hen in a place out of the sun, and lay white cloth everywhere in that place. The crows that hatch from the eggs will be white.
Paullini was skeptical, and he didn’t even bother trying it.
