The Wolf in Sheep's Clothing

A Wolf in sheep's clothing is an idiom of Biblical origin used to describe those playing a role contrary to their real character with whom contact is dangerous, particularly false teachers. As a fable it has been falsely credited to Aesop and the theme is now numbered 451 in the Perry Index. The confusion has arisen from the similarity of the theme with fables of Aesop concerning wolves that are mistakenly trusted by shepherds; the moral drawn from these is that one's basic nature eventually betrays itself.

The phrase originates in a sermon by Jesus recorded in the Christian New Testament: Beware of false prophets, which come to you in sheep's clothing, but inwardly they are ravening wolves (Gospel of Matthew 7:15, King James Version). The sermon then suggests that their true nature will be revealed by their actions (by their fruits shall ye know them, verse 16). In the centuries following, the phrase was used many times in the Latin writings of the Church Fathers and later on in European vernacular literature. A Latin proverb also emerged, Pelle sub agnina latitat mens saepe lupina (Under a sheep’s skin often hides a wolfish mind). Although the story of a wolf disguised as a sheep has been counted as one of Aesop's Fables in modern times, there is no record of a fable with this precise theme before the Middle Ages, although there are earlier fables of Aesop in Greek sources to which the Gospel parable might allude.

The first fable concerning a wolf that disguises itself in a sheep's skin is told by the 12th-century Greek rhetorician Nikephoros Basilakis in a work called Progymnasmata (rhetorical exercises). It is prefaced with the comment that 'You can get into trouble by wearing a disguise' and is followed by the illustrative story. 'A wolf once decided to change his nature by changing his appearance, and thus get plenty to eat. He put on a sheepskin and accompanied the flock to the pasture. The shepherd was fooled by the disguise. When night fell, the shepherd shut up the wolf in the fold with the rest of the sheep and as the fence was placed across the entrance, the sheepfold was securely closed off. But when the shepherd wanted a sheep for his supper, he took his knife and killed the wolf.' The conclusion drawn is different from the Gospel story. In the former one is warned to beware of hypocritical evil-doers; Nikephoros warns that evil-doing carries its penalty.

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