A large Wolf was nicknamed Lion. Believing this he moved to live with Lions. A Fox observed he might be a lion among wolves; but, was a wolf among lions.
Know yourself and your limits.

Townsend version
At one time a very large and strong Wolf was born among the wolves, who exceeded all his fellow-wolves in strength, size, and swiftness, so that they unanimously decided to call him “Lion.” The Wolf, with a lack of sense proportioned to his enormous size, thought that they gave him this name in earnest, and, leaving his own race, consorted exclusively with the lions. An old sly Fox, seeing this, said, “May I never make myself so ridiculous as you do in your pride and self-conceit; for even though you have the size of a lion among wolves, in a herd of lions you are definitely a wolf.”

Babrius Translation
A fine-grown wolf his tribe in size outvied,
The rest surnamed him “lion.” Puff’d with pride
He could not bear renown, but left his kin,
And with the lions friendship strove to win.
Then said a jeering fox, “From me be far
“That frenzy, in the mists of which you are.
“For you, no doubt, to wolves a lion seem,
“But lions count you wolf, in their esteem.”

Lupus et Leones
Lupus quidam robustior inter lupos natus erat, quem “Leonem” cognomine vocabant. Stolidus ille, et gloriae impar ferendae, a tribulibus segregavit se ac cum leonibus conversabatur. Vulpes autem, cavillatrix, “Ne ad sanam mentem tantum,” inquit, “sim umquam reducenda, quantum tu nunc vano fastu intumescis! Quippe qui inter lupos revera leo videris, interque leones rursus comparatione fis lupus.”
Perry #344