The French idiom ‘montrer patte blanche’ translates word by word as ‘to show a white paw’. However, the meaning of the idiom is equivalent to the English ‘to show your credentials’.
This expression was made popular by a fable of ‘La Fontaine’ about a wolf, a goat and its kid (Le Loup, la Chevre et le Chevreau). Left at home alone, the goat told its kid that it could only open the door to an animal with a white paw, so that the wolf, with grey paws, would not be able to enter.
This idiom can be used in contexts such as being able to gain access to a building, for example ‘Pour entrer, il faut montrer patte blanche’ meaning ‘To enter, one must show a white paw (credentials/present papers)’.
Other uses of the idiom can be to ‘appear open’, ‘be clean’, ‘be honest’ and to ‘redeem oneself’.
The foundation of this idiom is an old French fable, similar to the English idiom ‘to cry wolf’ which, though different in meaning, is also based on a fable, which shows similarities in the ways in which idioms are formed in both the English and French language.
Sources:
Collins- easy learning- French Idioms- 2010- Page 53
Language Portal of Canada
Wikipedia
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