Aristophanes
Definition.com
A Demagogue is in possession of a screeching, horrible voice, a perverse, crossgrained nature and the language of the market-place.
Definition.com
A Demagogue is like a fisher for eels. In still waters he can catch nothing, but if he thoroughly stirs up the slime, his fishing is good... in the same way it's only in troublous times that the demagogue lines his pockets.
Definition.com
A Demagogue is necessarily neither an educated nor an honest man... he has to be an ignoramus and a rogue.