It's the character of the speaker that does the persuading, not eloquence.
τρόπος ἔσθ᾿ ὁ πείθων τοῦ λέγοντος, οὐ λόγος.
Original text (Ancient Greek)
More quotes by Menander
The truth, sometimes not sought for, comes forth to the light.
Man must be prepared for every event of life, for there is nothing that is durable.
Men are taught virtue and a love of independence by living in the country.
Of all wild beasts on earth or in sea, the greatest is a woman.
Attribution
Quote text and notes from Wikiquote: Menander (page history), available under CC BY-SA 4.0. Source quality and labels are our own summary of what Wikiquote records.