Let no man be another's who can be his own
Final sentence from Aesop ascribed fable (see also Aesop's Fables) "The Frogs Who Desired a King" as appears in the collection commonly known as the "Anonymus Neveleti" (fable XXIb. De ranis a Iove querentibus regem). Motto of Paracelsus. Usually attributed to Cicero.