Marcus Tullius Cicero,
Cicero's Brutus or History of Famous Orators…
“ But as I am not seeking a pupil to instruct, but an Orator who is to be the model of his profession, he must have the preference who can always discern what is proper and becoming. For Eloquence should, above all, things, have that kind of discretion which makes her a perfect mistress of time and character: because we are not to speak upon every occasion, or before every audience, or against every opponent, or in defence of every client, and to every Judge, in the same invariable manner. ”
