"Of the modes of persuasion furnished by the spoken word there are three kinds. The first kind depends on the personal character of the speaker [ethos]; the second on putting the audience into a certain frame of mind [pathos]; the third on the proof, or apparent proof, provided by the words of the speech itself [logos]. Persuasion is achieved by the speaker's personal character when the speech is so spoken as to make us think him credible."
(Aristotle 1356a 2,3, translation by W. Rhys Roberts)
Aristotle, Book I - Chapter 2 : Aristotle's Rhetoric (hypertextual resource compiled by Lee Honeycutt)