Aesop's Fables (1884)
76. The Fox and the Leopard.
The Fox and the Leopard disputed which was the more beautiful of the two. The Leopard exhibited one by one the various spots which decorated his skin. The Fox, interrupting him, said: "And how much more beautiful than you am I, who am decorated, not in body, but in mind."
People are not to be judged by their coats.
Aesop's Fables: A New Revised Version From Original Sources (translator not identified), 1884 . Illustrations by Ernest Henry Griset (1844-1907), John Tenniel (1820-1914) and Harrison Weir (1824-1906). Available online at Project Gutenberg.