There is a real difference between describing a public health crisis as an epidemic and calling it a plague. As far back as we can go in the European tradition, words associated with ‘plague’ carry an extra charge; they connote something more than accident and bring into the account we give of medical disaster the suggestion of some kind of personal agency. Homer's Iliad famously starts with a picture of disaster, sickness striking the Greek troops under the walls of Troy, and shows us the god Apollo unleashing his arrows against animals and human beings, in revenge for an insult offered to one of his priests. In the first book of the Iliad, the sickness is variously called nousos, loimos and loigos: roughly, a disease, an outrage or injury, and a disaster or devastation – though Homer does use plege elsewhere, the origin of the Latin plaga – a blow or stroke. Simple description gives way to a mode of speaking that is not only dramatically personal but also moralised: sickness is not only connected with someone's agency but is understood as a moral consequence of events, a punishment.