Aesop
The Fox and the Mask
A Fox had by some means got into the store-room of a theatre.
Suddenly he observed a face glaring down on him and began to be
very frightened; but looking more closely he found it was only a
Mask such as actors use to put over their face. "Ah," said the
Fox, "you look very fine; it is a pity you have not got any
brains."

Outside show is a poor substitute for inner worth.