'The Frog and the Fox' (or 'The Quack Frog'), an illustration by John Vernon Lord in Aesop's Fables, Jonathan Cape, 1989, page 81.
The Frog, who Claimed he was a Physician, and the Fox
A FROG made proclamation to all the beasts of the forest that he was a skilful physician, and could cure all manner of diseases. This discourse uttered in a learned jargon of hard and cramped words, which nobody understood, made the beasts admire his learning, and give credit to his vauntings. At last the Fox asked him, with much indignation, how he, with his thin lantern jaws, speckled skin and disfigured body, could set up for one able to cure the infirmities of others.
Moral: We should not attempt to correct in others the faults peculiar to ourselves.
Text: Samuel Croxall (43, 1722) adapted by G. F. Townsend (3, 1866)
Selected parallels: Babrius 120. Avianus 6. L’Estrange 1/225. Chambry 69. Perry 289. TMI J1062.1.