„It is said, for example, that dragons can sometimes have seven heads. That is sheer nonsense. A dragon can have only one head, for the simple reason that having two leads to disagreement and violent quarrels; the polyhydroids, as the scholars call them, died out as a result of internal feuds. Stubborn and headstrong by nature, dragons cannot tolerate opposition, therefore two heads in one body will always bring about a swift death: each head, purely to spite the other, refuses to eat, then maliciously holds its breath- with the usual consequences.”
Stanislaw Lem, „The Cyberiad”.