"Medea mixed her poisoned aconite, brought with her long ago from Scythia's shores, said to be slobbered by the Hound of Hell. There is a cavern yawning dark and deep, and there a falling track where Herakles dragged struggling, blinking, screwing up his eyes against the sunlight and the blinding day, the hell-hound Cerberus, fast on a chain of adamant. His three throats filled the air with triple barking, barks of frenzied rage, and spattered the green meadows with white spume. This, so men think, congealed and, nourished by the rich rank soil, gained poisonous properties. And since they grow and thrive on hard bare rocks the farmfolk call them 'flintworts' -aconites." -Metamorphoses 7.408-419