The passions are the only advocates which always persuade. They are a natural art, the rules of which are infallible; and the simplest man with passion will be more persuasive than the most eloquent without.
Les passions sont les seuls orateurs qui persuadent toujours. Elles sont comme un art de la nature dont les règles sont infaillibles; et l'homme le plus simple qui a de la passion persuade mieux que le plus éloquent qui n'en a point.
Original text (French)
Variants
The passions are the only orators who always persuade. They are like a natural art, of which the rules are unfailing; and the simplest man who has passion will be more persuasive than the most eloquent man who has none.