Fear of mice avoid a mouse, showing there may be some basis for this belief. It is not known why elephants should react in this way, though there are several theories. Regardless, elephantine murophobia remains the basis of various jokes and metaphors. The classical board game Dou Shou Qi has the Rat kill an Elephant: as multiple editions of the rule book mentions that the Rat would crawl into the Elephant's ears to gnaw into its brain: but this is considered to be a folk tale. Gertrude of Nivelles is the patron saint of murophobia, and is also invoked against rats and mice
Abnormal profit Abnormal profit In economics, abnormal profit, also called excess profit, supernormal profit or pure profit, is "profit of a firm over and above what provides its owners with a normal (market equilibrium) return to capital." Normal profit (return) in turn is defined as opportunity cost of the owner's resources. A related broader term is economic rent, which applies to the owner of a resource, such as land, rather than to the firm as such. According to the theoretical model of perfect competition, abnormal profits are unsustainable because they stimulate new supply, which forces down prices and eliminates the abnormal profit.