Since the oldest rhetorical treatises the persuasive power of the ethos of the speaker has been a certainty.At the beginning of his Rhetoric Aristotle considers the π στιζ δι τo θ0ζ"almost,so to speak,the controlling factor of persuasion"(Rhet.1356 a 13).Cicero,on his side,has Antonius claiming in De oratore that the ethos and the behavior"of those who do the playing and of those on whose behalf they plead,make an important contribution to winning a case"(De Orat.2.182).What is different,however,is how the ethos can attain persuasion.Aristotle ascribes to the ethos of the speaker a rational effect on the hearers,who believe"more and more quickly"the honorable speaker who through his speech appears credible.Cicero,on the contrary,links the persuasive power of the ethos with the arousal of the goodwill of the hearers.We may wonder whether also Aristotle takes into account an emotive function of the ethos or Cicero also a rational one.I shall argue in this paper that if Aristotle does when dealing with the precepts of the introduction,Cicero does not,even if some details in Antonius description of the ethos of the speaker during his speech seem to recall Aristotles doctrine Indeed in the Latin rhetoric the challenge of rationality and emotions ends with the victory of emotions.