Perry's Index to the Aesopica
Fables exist in many versions; here is one version in English:
THE FOX, THE DONKEY AND THE LION SKIN
A donkey put on the skin of a lion and went around frightening all the animals.
The donkey saw a fox and tried to frighten her too, but she had heard his voice
first, so she said to the donkey, 'You can be sure that I too would have been
afraid, if I had not already heard the sound of your bray.'
Likewise, there are certain ignorant people whose outward affectations give
them an air of importance, but their true identity comes out as soon as they
open their big mouths.
Aesop's Fables. A new translation by Laura
Oxford University Press (World's Classics): Oxford, 2002.
cover, with new ISBN, published in 2008; contents of book unchanged.
In Perry 188, a donkey puts
on a lion's skin and scares the other animals, but the fox realizes
that the creature still brays like a donkey. In Perry
358, the donkey in a lion skin is able to scare the farmers
so that he can graze freely, but the wind blows the skin off, so
that the farmers realize their mistake and punish the donkey (or,
as in Avianus, the man grabs the
"lion" by his donkey ears; in Odo,
the farmers first recognize the donkey's braying, and then see his
donkey tails and hooves).
Perry 188: Gibbs (Oxford) 322 [English]
Perry 188: Jacobs 49 [English]
Perry 188: Townsend 244 [English]
Perry 188: Chambry 267 [Greek]
You can find a compilation of Perry's index to the Aesopica in the gigantic appendix to his
edition of Babrius and Phaedrus for the Loeb Classical Library
(Harvard University Press: Cambridge, 1965). This book is an absolute must for anyone interested
in the Aesopic fable tradition. Invaluable.