Plato on rhetoric, from Gorias, one of the Socratic Dialogues written around 380 BC.
Socrates: And now let us have from you, Gorgias, the truth about rhetoric: which you would admit (would you not?) to be one of those arts which act always and fulfil all their ends through the medium of words?
Soc. Words which do what? I should ask. To what class of things do the words which rhetoric uses relate?
Gor. To the greatest, Socrates, and the best of human things.
Soc. That again, Gorgias is ambiguous; I am still in the dark: for which are the greatest and best of human things? I dare say that you have heard men singing at feasts the old drinking song, in which the singers enumerate the goods of life, first health, beauty next, thirdly, as the writer of the song says, wealth honesty obtained.
Gor. Yes, I know the song; but what is your drift?
Soc. I mean to say, that the producers of those things which the author of the song praises, that is to say, the physician, the trainer, the money-maker, will at once come to you, and first the physician will say: "O Socrates, Gorgias is deceiving you, for my art is concerned with the greatest good of men and not his." And when I ask, Who are you? he will reply, "I am a physician." What do you mean? I shall say. Do you mean that your art produces the greatest good? "Certainly," he will answer, "for is not health the greatest good? What greater good can men have, Socrates?" And after him the trainer will come and say, "I too, Socrates, shall be greatly surprised if Gorgias can show more good of his art than I can show of mine." To him again I shall say, Who are you, honest friend, and what is your business? "I am a trainer," he will reply, "and my business is to make men beautiful and strong in body." When I have done with the trainer, there arrives the money-maker, and he, as I expect, utterly despise them all. "Consider Socrates," he will say, "whether Gorgias or any one-else can produce any greater good than wealth." Well, you and I say to him, and are you a creator of wealth? "Yes," he replies. And who are you? "A money-maker." And do you consider wealth to be the greatest good of man? "Of course," will be his reply. And we shall rejoin: Yes; but our friend Gorgias contends that his art produces a greater good than yours. And then he will be sure to go on and ask, "What good? Let Gorgias answer." Now I want you, Gorgias, to imagine that this question is asked of you by them and by me; What is that which, as you say, is the greatest good of man, and of which you are the creator? Answer us.
Gor. That good, Socrates, which is truly the greatest, being that which gives to men freedom in their own persons, and to individuals the power of ruling over others in their several states.
Soc. And what would you consider this to be?
Gor. What is there greater than the word which persuades the judges in the courts, or the senators n the council, or the citizens in the assembly, or at any other political meeting?-if you have the power of uttering this word, you will have the physician your slave, and the trainer your slave, and the money-maker of whom you talk will be found to gather treasures, not for himself, but for you who are able to speak and to persuade the multitude.
Soc. Now I think, Gorgias, that you have very accurately explained what you conceive to be the art of rhetoric; and you mean to say, if I am not mistaken, that rhetoric is the artificer of persuasion, having this and no other business, and that this is her crown and end. Do you know any other effect of rhetoric over and above that of producing persuasion?
Gor. No: the definition seems to me very fair, Socrates; for persuasion is the chief end of rhetoric.